The hosts were the better side in the first half and they went in at the break courtesy of Mame Biram Diouf's excellent lay-off and header.
In the second half Frankfurt were reduced to 10 men when Martin Lanig picked up his second yellow card, and Szabolcs Huszti wrapped up the points with a superb free kick.
Read how the action unfolded below.
2.01pmHello Bundesliga fans! We have our usual Sunday double-header for you tonight. Gladbach vs. Freiburg is later on but up first we have Hannover vs. Frankfurt.
2.03pmGermany's Europa League competitors - Freiburg and Frankfurt - have both struggled so far this season. Hannover's home record is keeping them above the drop zone for now, but they have even stuttered there in the last few weeks and are definitely looking over their shoulders.
2.06pmThey have lost four of six in the league and have failed to win each of their last two at HDI-Arena. On paper, against another side woefully short of confidence, this should be a win. Frankfurt managed a good win against Bordeaux on Thursday night, but have just three points from 18 in the league.
2.09pmIndeed, both sides will be eyeing this fixture as the chance to start to edge away from the bottom three. Frankfurt are above Freiburg on goal-difference only but could put pressure on their direct rivals ahead of their match with Gladbach straight after this.
2.11pmWell then, now we've looked at what a pickle the two sides are in, let's take a look at who the coaches have selected to get them out of it...
2.21pmSo what can we make from those teams? Well, I think that Mirko Slomka is going for it in this home game. He could not decide which striker to start, Mame Biram Diouf or Arthur Sobiech, so they are both in the XI. Edgar Prib starts at left-back, which is an interesting decision as he is naturally a winger.
2.24pmFrankfurt will need Vaclav Kadlec to pick up the form he managed early in the season. He starts up top with support from Tranquillo Barnetta and Takashi Inui. If Hannover are not alert that is a very dangerous attacking trio.
2.27pmBut what do I think? I know that's the main question here. It's a tough one, as Frankfurt will have been boosted by their Europa League win, but I think Hannover's record at home will see them to a narrow win. Let's say 2-1.
1 minKICKOFF: We're underway, Hannover kick us off and put it straight out of play for a goal kick. It can only get better from there.
4 minIt is a positive start this for the hosts. They are passing it around neatly among defence and midfield and Frankfurt, in their change blue strip, cannot get a touch at the moment. However, it's given away to Inui but Sakai is in well to win it back.
6 minLanig, the match-winner against Bordeaux for Frankfurt, has come off the pitch to receive treatment after an aerial clash. I don't think he was bleeding but he certainly took a knock on the lead. He's quickly back on now though.
9 minBLOCK! Good move there from Hannover and nearly the opening goal. Diouf finds Schmiedebach to his right, who puts it into the path of Andreasen, but his effort is blocked wide. From the corner Marcelo wins it but puts his header over.
13 minHannover are still just about on top here, but it has just been the one chance for them so far. Slomka will be pleased with the way his team have gone about their business and Frankfurt are getting a little scrappy trying to win possession.
16 minIt has been the final pass that has been lacking so far from Hannover. The movement between the front two has been interesting - Diouf has pushed right up while Sobiech has looked to drop into space.
19 minSomething of a half-chance there for the visitors this time as a corner is not cleared by Hannover and the shot on the turn from Barnetta is deflected and away to safety. That has been their first hint of goal so far.
22 minFrankfurt are looking a bit more threatening now and Schrock in particular down the right is coming into the game a lot. So far Hannover have dealt with his crosses but I suspect one to get through before too long.
24 minThat is exactly what you expect from Diouf - a typical goal from him. First he wins a header to ping the ball wide to Prib, who gets to the byline before whipping in a cross for the Senegalese to power an unmarked header past Trapp. They deserve the lead, too.
27 minDiouf has not been at his prolific best this season - far from it, in fact - but that is why Slonka has to pick him when fit.
28 minA really late decision to disallow that goal there - the players had celebrated and the referee did not see his assistant's flag for a long time. Diouf rose high to flick on to Sobiech and his shot was spilled in by Trapp, but the Senegalese was penalised for a foul on Flum. No-one appealed and there really looked nothing in it! That's a bad decision.
31 minI've seen another couple of replays but can't see much of anything from Diouf. His knee was up a bit I suppose, but that was because of the sheer height he managed with his leap. Sobiech and Diouf were furious and I can see why.
34 minI'm hearing that the decision could have been because of offside - but from Diouf and not Sobiech. That seems unlikely to me, it really does, but I'm sure I'll see it again before long. Meanwhile, Frankfurt are still struggling to get into the game.
35 minBOOKING: Barnetta, with full Movember moustache that makes him look very Freddie Mercury, goes into the book for a foul on Andreasen.
37 minOn the next free kick Andreasen takes a run up and smacks it straight into the wall. Whoever that hit in there it must have hurt a lot because it was travelling. Inui looks to go past Sakai, but the latter wins the battle of the Japanese and gets it out of play.
39 minAndreasen really fancies a goal tonight and he has another effort here from about 25 yards out. This time it isn't blocked, but his low drive skids wide of Trapp's right-hand post.
41 minCHANCE! That probably should be a goal there. The corner comes in and on the turn Schrock has a go with his left foot but it's blocked from close range.
42 minBOOKING: Deserved yellow there for Lanig, who goes up elbows first into an aerial challenge with Marcelo.
44 minCLOSE! Oczipka will claim that he meant that but his header from a free kick going up with Andreasen goes narrowly over his own bar. It could have been 2-0, but Frankfurt survive.
45 minJust one minute will be added on at the end of the half. I think it will end 1-0.
3.18pmWell that was definitely an entertaining first half and the correct team is winning at the break. It should be two really, but for a baffling decision to disallow a second goal - I still don't quite know why.
3.22pmFrankfurt simply haven't been good enough. The disallowed goal is a let-off for them, but without improvement at the back and especially up front they don't have a hope of getting back in this.
3.26pmHannover have been able to shut out their visitors so far, with Marcelo and Schulz comfortable in the air and against the ground threat so far. We might see a change from Frankfurt at the break, although Armin Veh might want to give it another 15 minutes.
46 minJoselu is on for Shrock at the break. Clarification on that goal was that Diouf did not flick the ball on and that Sobiech was offside from Zieler's initial kick. If that's right and Diouf didn't get a touch then that is a fantastic call.
48 minBOOKING: Marcelo goes up for a header a little exuberantly and goes into the book for his challenge. Seems fair enough to me.
50 minBOOKING: Another card and this time for Carlos Zambrano and that is a quite awful challenge. Very mistimed and this is a scrappy start to the half.
54 minStill very scrappy at the moment, with neither side able to get on top. Frankfurt have been slightly better, with a Joselu header going straight at Zieler, but it's about right that we haven't had a goal this half.
57 minRED CARD! Lanig picks up his second yellow card for what frankly could have been a straight red! He ripped through Sobiech from behind and there was no hope of him getting the ball. He maybe touched it first but you can't slide in from that angle.
61 minWe're even on the shot count here, which shows Frankfurt's improvement after the break. They're a man down now, of course, but are still putting up a real effort on the pitch.
64 minFRANKFURT SUB: Marvin Bakalorz comes on for Unui, as Huszti curls a free kick wide of the near post for the hosts.
66 minFrankfurt want a penalty but the referee waves play on! Schwegler went down in the box under very minor pressure from Sakai before Barnetta gave away a free kick outside his own box at the other end. Veh is furious and is getting a talking to - in fact he's off to the stands.
67 minWonderful hit from the Hungarian. Trapp doesn't move and Huszti clips it over the wall back to where the keeper was coming from and he finds the very, very top corner. What a superb strike!
70 minHANNOVER SUB: Leonardo Bittencourt is on for Sobiech, and he will play slightly deeper than the striker who made way.
73 minFRANKFURT SUB: Zambrano is trudging off the pitch for Marc Oliver Kempf.
76 minI think the stuffing has been knocked out of Frankfurt now. Their tempo before the second goal has completely gone and there only looks to be one side likely to score again. Even at 2-0 up Bittencourt is having to gee up the fans - strange, that.
78 minHannover are just holding on to the ball now. Which is fine - it's up to the visitors to start pressing the issue now if they don't want to lose this one.
81 minA couple of half-chances there for Frankfurt. A shot in the box from Kempf s blocked for a corner, before Schrock shoots from range and skids his effort wide.
83 minCHANCE! What a chance for Kadlec! Bakalorz plays him in with a fine through ball. He's slightly wide, but cuts on to his left and I think Zieler must have got a touch on it to put it wide as it goes for a corner.
86 minFrankfurt will feel unlucky to lose this, and they have certainly been the much better side after the break. But they were always chasing the game after the first goal and the red card made it an even tougher task.
89 minHANNOVER SUB: Final change for Hannover then as Jan Schlaudraff comes on for the last few minutes for Diouf. The Senegalese has had a great game.
90 minCLOSE! Great effort from Bittencourt. Schlaudraff drives forward and finds the youngster to his left, who fizzes a dipping effort just wide via a deflection. That was not in fact their final change - this is as Steven Cherundolo comes back. He's on for Huszti.