It was Argentina's Del Potro who made it through to the last four in a match full of incident from start to finish.
Read how all the drama unfolded in our game-by-game updates below.
12.31pmAfternoon everyone. Surely one of the highlights of the two weeks at the All England Club is here - it's men's quarter-final day!
12.33pmThere's four mouth-watering contests but before we get to them there could be some news regarding our feature match here between Ferrer and Del Potro...
12.36pmReports coming out of Wimbledon are saying that Ferrer had an almost non-existent warm-up this morning and could be carrying a knock. Here's a tweet from Press Association reporter Paul Hirst: "Injury scare for David Ferrer as he cuts short his practice session on Court 16 at #Wimbledon."
12.40pmIf I hear any more on that story I'll bring it to you as soon as possible, of course.
12.42pmAs I mentioned, there are four great games at Wimbledon today. First up on Centre we have this match and that's followed by home favourite Andy Murray against unseeded Spaniard Fernando Verdasco.
12.45pmOver on the second showcourt, No. 1 Court, proceedings open with world number one Novak Djokovic against Tomas Berdych before an all-Polish clash between Lukasz Kubot and Jerzy Janowicz. We're covering all four here on SM and I'll direct you to the page once the Djokovic-Berdych commentary goes live.
12.50pmNo further news on that possible Ferrer injury with the players due on court in 10 minutes' time.
12.53pmWEATHER WATCH! We had a rain-interrupted day on ladies' quarter-final day yesterday but it looks like the wet weather is staying away today. The latest forecast suggests that the sun might not break through the clouds but those clouds aren't of the rainy kind.
12.57pmAs mentioned above, both Ferrer and Del Potro, seeded fourth and eighth respectively this year, have never made it past the last eight at Wimbledon. Ferrer made it this far last year while this is Del Potro's first appearance in the All England quarters.
1pmPREDICTION! We're moments away from the from two Hispanic men walking out so I think it's about time for my prediction. I'm siding with DelPo because of this possible knock that Ferrer is carrying. The Spaniard is also not completely at home on the grass and I think that Argentinian Del Potro has a game better suited to the turf.
1.03pmThe two men are out on court now and beginning their warm-ups. The Royal Box in Centre Court is dominated by big names from the football world today with England manager Roy Hodgson and retired Manchester United legend Sir Alex Ferguson sharing a hug.
1.08pmAS IF! Ferrer and Del Potro met at SW19 a year ago to the day in the last 16. Read what happened here.
1.10pmAnyway, enough pre-match waffle. We're ready to go and it will be Ferrer to serve first. Ready, PLAY!
1.11pmThe first point goes Del Potro's way as, after an extended rally, Ferrer nets a forehand.
1.12pmTwo early BREAK POINTS for Del Potro...
1.13pmOH! Del Potro tries his hardest to track down Ferrer's volley and slides over on his angle and then falls awkwardly. He stays down and this doesn't look good at all.
1.14pmThe Argentinian's box is looking very concerned and the body language of Del Potro is not encouraging as the doctor assesses the damage.
1.15pmHis left knee is already heavily strapped and that looked like a hyper-extension of his knee.
1.15pmHe finally gets up on his feet and trudges back to his chair where we're now waiting for the doctor to be called.
1.16pmThe crowd gave him a warm round of applause when he got back up but he's got his head in his hands and it looks like he's going to have to retire after just five points.
1.18pmThe doctor asks Del Potro "where does it hurt?" His knee mate!
1.19pmThe murmurings are getting louder and louder in the Centre Court crowd as the fans try to work out if this match is already over.
1.19pmA smattering of applause goes round as he stands up briefly and is then handed a pair of painkillers. Ferrer is back on the baseline and DEL POTRO IS GOING TO GIVE IT A GO...
1.20pmIt's still break point for Del Potro at 30-40 and the pair have a long rally that can't be good for Del Potro. Ferrer manages to save the point with an up-the-line forehand that just lands in.
1.21pmDel Potro is struggling to sprint towards his backhand and that dodgy left knee but a big return brings us back to deuce.
1.22pmA DOUBLE FAULT from Ferrer on his second game point and we're back to deuce again.
Ferrer 1-0* Del PotroA first serve out to Del Potro's uneasy wing wins the game for Ferrer and Del Potro is going to have a go serving. He still looks so uncomfortable.
1.25pmFerrer knows that Del Potro can't run to his backhand and hits a return there that the Argentinian labours to and barely reaches. Surely he can't play on like this, unless those painkillers he was given take effect?
1.26pmIt sounds cruel, but if Ferrer wants a quick route to the last four then he should just pepper the Del Potro backhand.
Ferrer *1-1 Del PotroDel Potro's serve seems just fine as he holds to 15. Is he becoming a little more confident with every point?
1.28pmFerrer begins the third game with a forehand down the line that Del Potro again moves gingerly towards and doesn't even both to put a racket out for.
1.30pmIncredibly Ferrer double faults again and it's BREAK POINT Del Potro...
Ferrer 1-2* Del PotroBREAK! The injured man breaks first! The pair trade blows from the baseline before Del Potro launches a crosscourt forehand that lands inside the line. That's his fifth of the match and somehow he's broken.
1.32pmWhat must be going through Ferrer's head? He can clearly see that his opponent is far from 100% but he's behind! I think it's time for the Spaniard to start playing some drop shots to Del Potro's backhand side and really test that knee.
1.33pmFerrer does try a drop shot but it's to the forehand wing and Del Potro is able to reach it and prod a winner right into the corner. Excellent accuracy from the big man.
Ferrer *1-3 Del PotroFerrer did manage a winning drop shot in the middle of that game but he can't earn a break point as Del Potro rockets down his second ACE of the game to hold.
1.38pmBBC Sport's John McEnroe says that Del Potro's injury is such a shame because he's striking the ball so well at the moment. Too right.
Ferrer 2-3* Del PotroFerrer holds to 15 with a booming forehand winner that Del Potro doesn't bother trying to reach on his backhand. It's so hard to know what is going through Del Potro's head. Is he thinking that he might be able to somehow come through this or is he just trying to be as brave as possible, but ultimately knows that this match is over?
Ferrer *2-4 Del PotroDel Potro's big serve and forehand are ensuring that Ferrer doesn't threaten on his serve at the moment.
Ferrer 2-5* Del PotroDOUBLE BREAK! Amazing! Del Potro misses the easiest of volleys and crumbles at the net but then recovers to break the Spaniard again. He'll now serve for the opening set.
Ferrer 2-6 *0-0 Del PotroSET! Ferrer has a chance to earn one break back but he can't and Del Potro serves his third ACE at advantage to seal the set in 43 minutes. How he's doing this I'm not sure, but Ferrer needs to start turning nasty and target that backhand wing.
Ferrer 2-6 1-0* Del PotroA better start to the second set for Ferrer as he holds to 30 with Del Potro again looking menacing with those bullish groundstrokes.
Ferrer 2-6 *1-1 Del PotroIf Del Potro is still suffering badly from that knee injury he's showing it less and less as he holds to 15.
Ferrer 2-6 2-1* Del PotroMore big hitting from the Argentinian but he's just about hanging on to his serve and the lead in this second set.
Ferrer 2-6 *2-2 Del PotroA love hold from Del Potro that includes a sublime backhand up the line. He's hitting the ball so cleanly at the moment.
Ferrer 2-6 3-2* Del PotroDel Potro looks in the mood to break at 0-30 but Ferrer reels off the next four points to ensure there is still no break in the second set.
2.15pmUPDATE: Over on No. 1 Court, Djokovic has just come through a first-set tie-break 7-5 against Berdych.
Ferrer 2-6 *3-3 Del PotroBlimey, Del Potro is serving immensely here at 77% of first serves in. A second love-hold in a row for the Argentinian and Ferrer must be scratching his head wondering how to break serve here.
Ferrer 2-6 4-3* Del PotroDelPo broke twice and always looked menacing on Ferrer's serve in the first set, but it's not quite the same in the second as Ferrer holds by continuing his high first-serve percentage. Are we headed to a tie-break in this set?
2.21pmUPDATE: Berdych clearly hasn't let that first set loss dampen his spirit as he breaks Djokovic's serve straight away in the second.
Ferrer 2-6 *4-4 Del PotroWhoosh! It's a third hold-to-love in a row for Del Potro. He seals the game with a quite astonishing forehand pass with the ball almost behind him. He possesses immense power.
2.24pmAnother thunderbolt off the Argentinian's forehand wing and he's looking to make that crucial breakthrough, it's 15-30...
2.25pmFerrer answers with a mighty forehand off his own with Del Potro pinning him deep on the baseline.
2.26pmBREAK POINT Del Potro...
2.26pmBrilliantly saved by Ferrer. He goes for the surprise serve-and-volley and puts away a tough overhead. Deuce it is.
Ferrer 2-6 4-5* Del PotroBREAK! A superb return right to the feet of Ferrer earns Del Potro a vital break in the second set. He'll now serve for a two-set lead.
2.29pmUPDATE: As Del Potro breaks on Centre, Berdych has just opened up a double-break lead over Djokovic in the second set on No. 1.
2.30pmIf you manually refresh this page now, you'll be able to see a picture of Del Potro when he was struggling on the ground earlier. As if he's now a set and a break up!
2.32pmTWO SET POINTS for Del Potro thanks to a massive serve up the T.
Ferrer 2-6 4-6 *0-0 Del PotroSET! Ferrer returns well from another Del Potro first serve but the Argentinian clips a low slice over the net that Ferrer can't get back over himself.
2.34pmJust under 40 minutes that set took. Del Potro has won 31 of the 35 points when he's got his first serve in. Ferrer is regarded as one of the best returners in the game so that just shows you how well Del Potro's playing here.
2.36pmFerrer begins the third set with a down-the-line backhand winner and ACE out-wide. There's not many men on tour who wouldn't be too disheartened at going two sets down but Ferrer is a marathon man and can pull this off.
Ferrer 2-6 4-6 1-0* Del PotroA confident start to the third set from Ferrer, can he now break Del Potro for the first time this match?
Ferrer 2-6 4-6 *1-1 Del PotroErrrrm, nope. Del Potro holds to love and is looking unbreakable right now.
Ferrer 2-6 4-6 2-1* Del PotroDel Potro with a glimpse of a break at 15-30 but Ferrer wins the next two and edges ahead once more in the third.
Ferrer 2-6 4-6 *2-2 Del PotroDel Potro has only offered Ferrer two break points in this entire match and he's not about to supply any more as he holds to 30.
Ferrer 2-6 4-6 3-2* Del PotroAgain Del Potro moves to within two points of a break at 15-30 but Ferrer takes the next three, winning the game with a superb winner down the line and an encouraging shout of "VAMOS!"
2.53pmFerrer finds another wonderful backhand winner to bring it back to 15-15 on DelPo's serve.
2.54pmUPDATE: In the other quarter-final taking place, Djokovic has got both of those breaks against him back against Berdych and is now 5-4 ahead in the second.
Ferrer 2-6 4-6 *3-3 Del PotroAnother service hold for Del Potro as Ferrer shoots long with a forehand approach at 40-30. That's his 18th unforced error of the match. Del Potro has just six! Superb for a man who hits the ball so hard.
2.56pmUPDATE: Berdych had a double break and led 3-0 in the second against Djokovic, but he's just lost the set 6-4. Not good from the Czech.
Ferrer 2-6 4-6 4-3* Del PotroFerrer does what he does best to hold serve at 40-15. Del Potro is walloping the ball from side-to-side but Ferrer doggedly gets them all back before the Argentine doesn't move his feet too well and dumps a forehand into the net.
3pmIMAGE: Click here to see a picture of Sir Alex Ferguson chatting to England rugby coach Stuart Lancaster in the Royal Box.
Ferrer 2-6 4-6 *4-4 Del PotroDel Potro fires just long with a rocket forehand at 40-0 but holds serve on the next point thanks to a classic one-two punch. We're now at the same stage as when Del Potro made the crucial breakthrough in the last set. Can Ferrer hold his nerve this time?
3.03pmNot a good start to the game for the Spaniard as he swipes long.
3.04pmDel Potro may have just lost the following two points but he tracked down both of Ferrer's forehand's out-wide to his backhand and is clearly moving so much better to that wing than he was a couple of hours ago.
Ferrer 2-6 4-6 5-4* Del PotroFerrer does what he couldn't manage in the second by holding in the ninth game of the set. It's now over to Del Potro to serve to stay in the set.
3.08pmFerrer goes on the offensive and is now two points from the set at 15-30. Can Del Potro respond?
3.08pmOf course he can, ACE!
3.09pmA poor forehand from Ferrer and it's Del Potro who now has a game point.
3.10pmOdd moment as Ferrer's return is right at the feet of DelPo and he decides to just volley it full-on instead of letting it bounce to see if it goes out. A volley from the baseline is extremely tough and he can't direct it in so we're at deuce.
Ferrer 2-6 4-6 *5-5 Del PotroA pair of crashing serves see the eighth seed hold. Over to you, David.
3.12pmNaff start to the game for Ferrer as his easy backhand at the net wrongfoots Del Potro but goes wide!
3.13pmUPDATE: It's not looking good for Berdych over on No. 1 as Djokovic breaks in the third set and now just has to hold on to his serve to reach the semis.
Ferrer 2-6 4-6 6-5* Del PotroFantastic grit from Ferrer! It looks like Del Potro is about to earn a break point at 30-30 but Ferrer gets back in the rally and finds a forehand winner before delivering his eighth ACE of the match to hold.
Ferrer 2-6 4-6 6-6(*0-0) Del PotroSome way to assert your authority before a tie-break as Del Potro holds to love. There was an incredible forehand winner after a perfectly good Ferrer return in the middle of that.
THIRD-SET TIE-BREAKFerrer 1-0* Del Potro
THIRD-SET TIE-BREAKFerrer 1-1* Del Potro
THIRD-SET TIE-BREAKFerrer *1-2 Del Potro. Two aces in a row for Del Potro.
THIRD-SET TIE-BREAKFerrer *1-3 Del Potro. First mini-break to the Argentinian.
THIRD-SET TIE-BREAKFerrer 1-4* Del Potro. Another mini-break for DelPo and this is his to lose now.
THIRD-SET TIE-BREAKFerrer 2-4* Del Potro. Ferrer gets one back and the players change ends with Del Potro one mini-break ahead.
THIRD-SET TIE-BREAKFerrer *3-4 Del Potro. Ferrer wins two in a row against the serve as Del Potro misses an easy forehand.
THIRD-SET TIE-BREAKFerrer *4-4 Del Potro
THIRD-SET TIE-BREAKFerrer 4-5* Del Potro. Amazing return from Del Potro and he now has two serves to win the match...
THIRD-SET TIE-BREAKFerrer 5-5* Del Potro. Both men are cautious in that rally and it's Del Potro who falters. Back on serve.
THIRD-SET TIE-BREAKFerrer *5-6 Del Potro. WHAT A SHOT! Ferrer is all over the point but Del Potro finds an unbelievable crosscourt forehand and it's MATCH POINT...
Ferrer 2-6 4-6 6-7 Del PotroGAME, SET AND MATCH DEL POTRO!
3.28pmWhat a way to win it! Neither man wants to make an error and they trade cautious groundstroke after groundstroke before Ferrer takes on a crosscourt forehand. Del Potro is well wide of the court but manages to hit the ball over the highest part of the net and dip it back into the corner.
3.30pmA phenomenal way to win what was a gigantic effort from Del Potro. He's still yet to lose a set at this year's Championships.
3.32pmIf you've only just joined us and want a quick recap of that astonishing battle, here's our concise report.
3.34pmNext up for Del Potro is number one seed Novak Djokovic, who completed his victory over Tomas Berdych at basically exactly the same time over on No. 1 Court. Here's our report on that one.
3.35pmThat's all we've got time for on this commentary but make sure you look out for our coverage of the next two quarter-finals. They'll both be live on site very shortly. See you there.