Gelsenkirchen, Germany – Manuel Neuer was forced to make just 0 at the Veltins-Arena.
Neuer left Schalke this summer to join Bayern, but Germany's No. 1 goalie was not troubled in his first match back in Gelsenkirchen in a club jersey, as he posted his eighth straight shutout in all competitions and ninth overall.
Bayern returned to the top of the Bundesliga after slipping off the top after Saturday's matches and has already established a plus-17 goal differential. In 10 games in all competitions this season, Bayern has outscored opponents 25-1.
With German international Mario Gomez sidelined with a groin injury, Petersen got his first Bundesliga start and provided the opening goal in the 22nd.
Franck Ribery set up the goal with a nice run on the break, and after he drew three defenders, found Petersen open on the right. Petersen's initial shot was saved by Schalke goalie Ralf Fahrmann, but his second chance found the net.
Petersen recovered the ball and drove a shot off a Schalke defender and into the left side for his second goal of the season.
Schalke's two good scoring chances came from Klaas-Jan Huntelaar later in the first half, but he fired wide of the left post in the 29th and 33rd as he did not test Neuer.
Muller slide a shot wide left in the 53rd after a nice set up by Philipp Lahm, but found the clinching goal in the 75th after nice work on the right by David Alaba and Ribery.
The ball took a lucky bounce off Ribery and a Schalke defender to find Muller, who drove a side volley inside the right post from close range for his first league goal this season.
While Bayern won its fifth straight in the league, Schalke lost for the third time as its record slipped to 3-3-0.
Hannover 2, Borussia Dortmund 1
Hannover, Germany - Karim Haggui and Didier Ya Konan scored in the 87th and 89th minutes, respectively, as Hannover snatched a 2-1 victory over Borussia Dortmund on Sunday at AWD-Arena.
Shinji Kagawa opened the scoring in the 63rd minute, but Hannover stunned the defending Bundesliga champions with two late goals.
Haggui headed Christian Pander's corner kick into the upper right to equalize, and Ya Konan followed by turning Sergio Pinto's cross to the bottom left with one minute left in normal time.
Hannover won its third of the season against one loss and two ties. Dortmund, which lost just five matches last season, lost for the third time through just six weeks.