Pierre-Emerick Aubameyang handed the control to the visitors with an 18-minute brace, before a stunning strike from Marco Reus extended Dortmund's lead later in the first half.
Adrian Ramos came off the bench late on to complete an emphatic display in style as Dortmund held onto their spot at the top of Group D.
Read below to find out how events unfolded.
6.45pmGood evening everyone. Group D continues this evening as Galatasaray host Borussia Dortmund, who can take a huge step towards reaching the next round with a victory this evening. Can Gala prevent Jurgen Klopp's side from keeping up their 100% record?
6.47pmIt's been a very strange start to the new season for Dortmund, who currently sit 14th in the Bundesliga. However, they've been impressive in claiming two wins in the Champions League and will be firm favourites to top the group if they pick up three more points tonight.
6.50pmGalatasaray have struggled so far in the competition. After being held to a 1-1 draw at home by Anderlecht on matchday one, they suffered embarrassment in North London earlier this month as Arsenal cruised to a 4-1 victory. Cesare Prandelli will be desperate to see a response tonight as they look to keep their qualification hopes alive.
6.53pmPrandelli's do head into this game full of confidence following a 2-1 triumph over fierce rivals Fenerbache on the weekend. Dortmund's morale is nowhere near the same level after their troubling domestic form continued with a 2-1 defeat to Koln, despite the returns of Marco Reus and Ilkay Gundogan. What kind of performance will Jurgen Klopp see from his players tonight?
6.55pmAs mentioned a moment ago, Reus and Gundogan are back for Dortmund following their respective injury problems. Both can be huge players for Dortmund if they are at the top of their game, and Klopp will be relying on the pair to inspire the others around them as the team looks to hit top form in Europe and in the Bundesliga. We'll find out in a few moments if they're in the team tonight.
6.59pmWe've seen over the years that Galatasaray are a very different prospect at home compared to their record on the road in Europe. A draw with Anderlecht last month was a disappointing result, but Dortmund will be fully aware how tough it can be to play in such a fiery atmosphere in Istanbul. If Gala are at their best, it will be a difficult evening for the German side.
7.02pmThe last time these two sides met in a European competition came in the UEFA Cup 14 years ago. Galatasaray claimed a goalless draw in the second leg in Istanbul to win the fourth round tie after goals from Hakan Sukur and Gheorghe Hagi had given them the advantage in Germany.
SUBSTITUTES: Bolat, Dzemaili, Bulut, Balta, Oztekin, Kurtulus, Colak
7.07pmAs expected, it looks like Prandelli will stick to the diamond formation for tonight's game. The Italian has decided there is no place in the starting lineup for Blerim Dzemaili or Umut Bulut, who are both named on the bench. Goran Pandev partners Burak Yilmaz in attack for the hosts.
7.14pmGundogan, who started for the first time in 15 months on Saturday, drops to the bench tonight as Sven Bender returns in midfield. Despite scoring in the defeat to Koln, Ciro Immobile is also denied a spot in the team as Pierre-Emerick Aubameyang starts in attack. Reus, Shinji Kagawa and Henrikh Mkhitaryan will provide support for the striker.
7.19pmWhat do we make of the two team selections? From looking at both sides, it looks like each manager is eager for his side to adopt a positive approach, which should hardly come as a surprise. Gala will be hopeful of frustrating Dortmund's attackers by getting men behind the ball, but they have the players to cause problems for the visitors. If Wesley Sneijder can link with Pandev and Yilmaz regularly, the hosts have a great chance tonight.
7.23pmAntonio Mateu Lahoz will be the man in the middle tonight and he'll be supported by his fellow Spanish officials. Let's hope they are not the people stealing the headlines this evening.
7.25pmYou can follow live text coverage of any of the Champions League games by clicking on the fixture in the scores box on the right of the page. For supporters of these two sides, it will be worth keeping an eye on Anderlecht vs. Arsenal as they look to close the gap on Dortmund at the top of Group D.
7.28pmIt's a huge night in the Champions League, there's no doubt about it. In truth, if Dortmund win tonight they'll feel that their spot in the next round is almost secure. A defeat for Galatasaray would almost certainly ruin their chances of progressing.
7.30pmPREDICTION: Kickoff is 15 minutes away in Istanbul, so it's time to have a guess what the score will be tonight. It's a tricky one to predict because of Dortmund's troubling form in the Bundesliga. Can Gala become the latest team to frustrate Klopp? It's going to be close and I'm going for an entertaining 2-2 draw.
7.34pmKEY BATTLE: It would be very easy to underline the importance of Reus tonight, but I think there's a good chance that the crucial contest will be between Bender and Sneijder. Dortmund can often dominate games with their ability to move the ball quickly, so when Galatasaray win possession, they must not waste opportunities. Sneijder is key to everything they do and Bender will be the man trusted to keep the Dutch playmaker quiet.
7.36pmFor those of you who did hear the news about Prandelli's ill-health this week, it has been confirmed that the Italian is inside the ground to lead his side tonight after skipping training and the pre-match press conference to go for some routine tests.
7.39pmThe home supporters are creating a fantastic atmosphere already as the two teams line up in the tunnel. You won't hear many Dortmund supporters tonight. Kickoff is just a few minutes away now.
7.44pmThe Champions League anthem has been played and the handshakes are out of the way in Istanbul. It will be Galatasaray who get the game underway.
1 minDecent start to the game from Galatasaray before Dortmund press further up the pitch to retrieve possession.
3 minA few heavy tackles have disrupted the flow of the match in the early stages as both sides look to stamp their authority on the contest. The hosts have seen more of the ball, but there's been very little action in attacking areas.
5 minKagawa finds space on the box, but he twice wastes the opportunity to deliver a cross as poor pass is followed by a needless back heel which is stopped by the home defence. A long ball forward almost picks out Yilmaz, but Dortmund goalkeeper Weidenfeller reacts quickly to clear the danger.
6 minGOAL! GALATASARAY 0-1 BORUSSIA DORTMUND (AUBAMEYANG)
7 minDortmund score a crucial early goal in Istanbul! Mkhitaryan's through ball plays in Reus on the left and he delivers the perfect cross to the back post, where Aubameyang has the simple task of tapping home from close range. What a start for the visitors.
9 minThe game has been played at a very high tempo in the early stages. Both sides were threatening on the counter before the goal, but the opener will force Galatasaray to attempt to take full control of the match. They need to respond. Sneijder has been very quiet so far.
11 minSokratis believes that he has been fouled in the middle of the pitch and decides to pick the ball up, but the referee frustrates the Dortmund defender by handing a free kick to the hosts. However, Galatasaray quickly lose possession once again.
13 minSubotic gets very lucky as his misplaced pass invites pressure from Gala, who waste a good opportunity to trouble the visiting defence. Dortmund have played a very high line early on, and look to be vulnerable to longer balls played into the channels.
14 minWeidenfeller comes off his line to punch a corner clear. Altintop attempts to catch the keeper off his line with a speculative volley, but he's few yards off target with the shot.
17 minMuch better from the hosts as they get the ball wide on two occasions to test Dortmund with a couple of dangerous crosses. Yilmaz and Pandev need service like that if they are to make an impact tonight.
18 minGOAL! GALATASARAY 0-2 BORUSSIA DORTMUND (AUBAMEYANG)
19 minAubamyeang strikes again for the visitors. It's all too easy for Dortmund as Piszczek collects the ball on the wing before delivering a cross for Aubameyang, who once again keeps his calm to convert from just a few yards out. Chedjou must take some of the blame after failing to stay close to the forward in the box.
21 minDespite seeing plenty of the ball, Gala can only blame themselves for handing the control to the visitors. Both goals were very, very simple and Aubameyang has twice been gifted the room to score the easiest of braces. A knock to Bender forces a break in play for a few moments, but the midfielder should be fine to continue.
24 minPrandelli will be getting increasingly frustrated with how often his side are losing possession at crucial times in the final third of the pitch. Dortmund have been happy to let the home defence pick their pass in the first half as they limit the space on offer in midfield.
25 minCHANCE! It could have been even better for the visitors. Reus collects the ball in space on the edge of the box and slides a pass into the path of Kagawa, whose weak effort is easily stopped by Muslera. Sneijder then picks up a booking at the other end for diving under pressure from Piszczek. Good refereeing from the Spanish official.
27 minGalatasaray win a free kick and all of the big men from the back are sent forward. However, Sneijder ignores his teammates in the box as he sends an awful effort into the stands from 35 yards out. Terrible from the Dutchman.
29 minDortmund are caught out playing the high line as a long ball reaches Yilmaz. Subotic responds brilliantly to tackle the forward, who should have unleashed a shot much earlier. Weidenfeller misses with a punch from the corner which follows, but the hosts can't take advantage.
31 minWOODWORK! Aubameyang is inches away from a hat-trick as he rattles the post from close range after Mkhitaryan had broken free in the box to send a powerful cross to the back post. It was Aubameyang's toughest chance, but he'll feel he should have scored again.
32 minIt hasn't been all Dortmund, but the visitors look dangerous every time they get forward. Mkhitaryan, Kagawa and Reus are being gifted too much room and Aubameyang will surely get more chances if his teammates continue to find pockets of space.
33 minIt's unclear what has upset Klopp, but the game has to be stopped for a few moments while the referee lectures the Dortmund had coach. 2-0 up in Istanbul is not the time to get sent to the stands.
35 minSemih almost gets into trouble when he slips as Aubameyang was threating to break free, but the Galatasaray defender manages to respond to get a vital foot on the ball. He could have been off had he got that challenge wrong.
37 minCHANCE! Mkhitaryan loses his marker once again to collect a great pass from Bender. Chedjou had lost the ball in an advanced position moments earlier, which created more space in the box. However, Mkhitaryan's cross is intercepted before it can reach Reus, who would have surely finished. Klopp is delighted with the move as he applauds from the sidelines.
40 minDortmund are enjoying an extended spell on top, but Gala manage to clear a couple of dangerous corners into the box. The hosts simply cannot afford to concede another goal if they are to have any chance of claiming anything from this game tonight.
41 minGOAL! GALATASARAY 0-3 BORUSSIA DORTMUND (REUS)
42 minYou won't see this very often. Large sections of the Galatasaray supporters are applauding Reus, who has just scored his side's third in spectacular fashion. The German playmaker is gifted the space to take aim 25 yards from goal, and he gives Muslera no chance with a swerving effort which finds the top corner. What a strike!
44 minIt's been clinical from Dortmund. They've scored three, despite spending much of the first half without the ball. Galatasaray are lacking ideas going forward as Melo's speculative strike from 30 yards is easily collected by Weidenfeller.
45 minSAVE! Mkhitaryan leaves two Galatasaray defenders behind him with an excellent run as he cuts in from the left before forcing Muslera into a good save with a powerful strike from outside the box.
45+2 minGalatasaray continue to see plenty of the ball in the second of two added minutes, but they're struggles in the final third of the pitch are quite unbelievable. Dortmund are gifted the ball once again as the hosts looked to create a rare chance.
8.34pmHALF TIME: GALATASARAY 0-3 BORUSSIA DORTMUND
8.36pmThe jeers from the home supporters are loud as the two teams head back down the tunnel. It's been a disastrous night so far for Galatasaray, who look to be on the way to another defeat. Dortmund have taken full advantage of the home side's defensive frailties with an Aubameyang brace and a wonder strike from Reus. There is surely no way back for Prandelli's side.
8.41pmWhat can Galatasaray do in the second half? Sneijder needs to get involved more often because the hosts have been unable to retain possession in the latter stages of their attacks. He's not made an impact and as a result, the front two of Pandev and Yilmaz have been very quiet. At the back, something must be done to prevent Reus, Kagawa and Mkhitaryan from finding so much space.
8.43pmIf you missed any of the first half, you can read Paul Gorst's roundup of a superb 45 minutes for Dortmund in Istanbul.
8.47pmThe players have emerged for the second half. You'd have to presume that Prandelli was far from happy at the break, but he's decided against making a change. Dortmund will get the game back underway.
47 minReus is once again gifted space to take his time on the ball. Fortunately for the hosts, the German is unable to play the perfect pass through a small gap for Mkhitaryan. Galatasaray can't continue to make the same mistakes.
48 minHummels is forced to concede a corner as the hosts enjoy a spell on top, but the danger is cleared from the set piece. Gala's defenders are being given time on the ball once again as Dortmund stick to the approach which brought them success in the first half.
51 minThe game is stopped to allow Bender to receive medical attention. He's been in the wars tonight and it looks like he was caught in the ribs as he clashed with Telles. There are options on the bench for Klopp if he thinks Bender must come off.
53 minSelcuk targets the top corner with a powerful strike from 25 yards, but the ball was always drifting just wide of the target. In truth, that's the closest the hosts have come to scoring tonight.
55 minSUBSTITUTION: Dortmund have been forced to play the last few minutes with 10 men on the pitch, but Matthias Ginter has now been sent on to replace the injured Bender.
57 minA few shots of the stands suggest that a lot of Galatasaray supporters elected to head home at the break. Their side are looking better in possession now, but they're struggling to trouble the Dortmund defence.
59 minCHANCE! Galatasaray twice fail to clear the danger on the right wing. Mkhitaryan eventually delivers the ball to the back post, but Reus is unable to keep his effort down as Muslera watches the ball sail over his crossbar.
60 minCHANCE! Reus wastes another opportunity to extend the lead as a misplaced pass from Semih sets up the attacking midfielder for a shot which is directed straight at the waiting hands of Muslera.
61 minSUBSTITUTIONS: Altintop, who has struggled with fitness issues this season, and Telles are removed by Prandelli as Yasin Oztekin and Blerim Dzemaili introduced to the action.
63 minDespite seeing Dortmund take their foot off the gas slightly in the second half, Galatasaray have still looked vulnerable as soon as the visitors apply any pressure on the ball. The pace of the game has slowed since the interval as the visitors cruise to what looks like an inevitable victory.
66 minCHANCE! It's exhibition football from the visitors as all of their attacking players get involved in some superb one-touch play. Mkhitaryan eventually shifts the ball to Kagawa, who drags a shot just wide from the edge of the box.
67 minIt looks like Galatasaray have switched to a 3-5-2 formation, with Oztekin now providing the width on the right. The substitute does find space on the wing, but his cross into the box is easily cleared by Hummels.
69 minYELLOW CARD! Mkhitaryan probably should play in Aubameyang, but he decides to take on Semih, who picks up a yellow card for a blatant foul as the attacking midfielder approached the box. Klopp then makes another change, with Hummels given a rest as he makes way for Gundogan.
70 minReus is forced to wait before he can try his luck from the free kick, but he's unable to find the top corner from a set piece as his strike drifts over the crossbar.
72 minGinter has been asked to fill in at centre back in the absence of Hummels, but he should be pretty comfortable in that position. Dortmund come close to making it 4-0 at the other end when Reus breezes past a couple of players before teeing up Mkhitaryan, whose low effort is well saved by Muslera.
74 minThere's plenty of options for Gundogan 25 yards from goal, but he ignores his teammates and fires a speculative effort straight at Muslera. Poor effort from the midfielder.
75 minUPDATE: Arsenal are trailing Anderlecht 1-0 in the other Group D fixture, which means that Dortmund will be five points clear at the top if the scores stay the same.
77 minSUBSTITUTE: Emre Colak is given a chance to impress in the closing stages as they ineffective Pandev jogs off the pitch to jeers from the home fans.
80 minSelcuk picks the perfect pass to find Oztekin on the right side of the box, but the substitute is caught in two minds as a powerful strike drifts a couple of yards wide of the far post. There's been a lack of intensity to this match in the second half, and Dortmund continue to look very relaxed on the ball.
82 minSUBSTITUTION: Kagawa appears to have suffered a hamstring injury and he has been forced to make way for Adrian Ramos. Klopp will be hoping the problem is not too serious.
83 minGOAL! GALATASARAY 0-4 BORUSSIA DORMUND (RAMOS)
84 minWhat an impact! Gundogan's clever turn in midfield allows him to find the space to spot the run of Ramos, who controls well before firing past a hopeless Muslera. It took the forward less than a minute to score after replacing Kagawa.
86 minReus attempts to help out his defenders, but a miscued interception forces Weidenfeller into a rare save. Dortmund then break quickly and are close to creating another chance when Aubameyang's cross just rolls past Mkhitaryan.
88 minIt's felt like a training session for the Dortmund players in the second half. There's barely been a response from the hosts, who have been absolutely woeful going forward tonight. Dortmund are dominating possession now as they cruise towards the final whistle.
89 minUPDATE: In the other Group D game, Arsenal have claimed a late equaliser against Anderlecht through Kieran Gibbs.
90 minMkhitaryan tries his luck with an optimistic half volley from the edge of the box, but he doesn't make the desired impact as the ball sails over the crossbar.
90+1 minThe fourth official confirms there will be just two minutes added on. Dortmund's lead at the top of the group is now likely to be three points, due to Arsenal's late heroics. The Gunners now lead Anderlecht 2-1 in Belgium.
90+2 minGalatasaray are seeing plenty of the ball in stoppage time, but they are still lacking a cutting edge in the final third of the pitch. It's been far too easy for the Dortmund defenders.
9.36pmFULL TIME: GALATASARAY 0-4 BORUSSIA DORTMUND
9.37pmIt's all over in Istanbul. Dortmund have kept up their 100% record in Group D with the most comfortable of victories over Galatasaray, whose hopes of reaching the knockout stages look to be over.
9.39pmThanks for joining me this evening. We hope you've enjoyed our coverage on another dramatic night in the Champions League. There will be analysis and reaction on the way from every one of tonight's games. Goodnight.