BERLIN (AFP) - Bayern Munich extended their unbeaten Bundesliga run to 34 games on Saturday by coming from behind for a 4-1 home win over Mainz to go back top of the Bundesliga.

Having last lost in the German league back in October 2012, Bayern are now just two matches short of Hamburg's 30-year-old, 36-match streak.

Bayern were punished for a poor first-half in Munich when Mainz striker Shawn Parker fired home after capitalising on a mistake by centre-back Jerome Boateng.

But Bayern roared back when Germany midfielder Mario Goetze came off the bench for the second-half and played a key part in the hosts' first three second-half goals.

"We really, really struggled in the first half and we tended to lack concentration," admitted Bayern captain Philipp Lahm.

"It happens frequently after international breaks, and we need to get a grip on it as soon as we can.

"We switched things around a little after that and it paid off, but credit to Mainz, they made life very difficult for us." Goetze made the difference and his dream pass through to Arjen Robben allowed the winger to equalise on 50 minutes and two minutes later, Goetze combined with the Dutchman for Germany's Thomas Mueller to fire home to make it 2-0.

With Bayern finally making their 80 per cent possession pay off, Goetze fired in a cross for Mario Mandzukic to score their third on 69 minutes.

And when Bayern vice-captain Bastian Schweinsteiger was fouled in the area, Mueller stepped up to drill home the penalty for his second of the game eight minutes from time to make it 4-1.

"We were like a 1970s VW Beetle and you can't dream of winning a race against a Formula One car," admitted Mainz coach Thomas Tuchel.

Bayern's win put them back on top of the Bundesliga after Bayer Leverkusen had briefly gone top on Friday thanks to a controversial 'phantom' goal in their 2-1 win at Hoffenheim.

The German Football Federation (DFB) are set to investigate while Hoffenheim have called for a replay after Stefan Kiessling's 70th-minute winner came in bizarre circumstances.

Replays showed his header only ended in the back of the net after flying through a hole in the side netting and a DFB sports court is set to meet on Monday.

Hertha Berlin went fourth after their 1-0 win at home to Borussia Moenchengladbach with Colombia's Adrian Ramos scoring the winner in the capital with a first-half header.

Schalke, who host Chelsea in the Champions League on Tuesday, needed a 91st-minute winner from Roman Neustaedter to seal a 3-2 win at bottom side Eintracht Braunschweig.

Having only picked up their first win of the season a fortnight ago against Wolfsburg, Braunschweig gave Schalke an almighty scare before Germany's Neustaedter hit the winner.

Borussia Dortmund, who are at Arsenal on Tuesday in the Champions League, stayed second with a hard-fought 1-0 win at home to Hanover 96.

Germany winger Marco Reus hit the winning penalty after just four minutes when Hanover's Japan defender Hiroki Sakai fouled left-back Erik Durm in the area.

Sakai was shown a yellow card for the foul and Reus blasted home the spot kick as Dortmund picked up the three points.

"I am happy with the result, we knew it would be difficult," said Dortmund coach Jurgen Klopp.

"We started well, but then got weaker, but for me it was decisive that the lads dealt with the situation.

"We can play better football and we will." Borussia stay second and level on 22 points with third-placed Leverkusen, just a point behind Bayern.

Second-from-bottom Freiburg picked up a point with a goalless draw at Werder Bremen, while Eintracht Frankfurt drew 1-1 at home to Nuremberg.

On Sunday, Hamburg host VfB Stuttgart and Augsburg are home to Wolfsburg.