(CNN) -- SV Hamburg regained top spot in the Bundesliga with a 1-0 win over Bayern Munich in Saturday's vital league clash in Germany.
Croatian international Petric scored the late winner to see off Bayern.
Mladen Petric scored the only goal of the game for the northerners in the 72nd minute after an assist from former Bayern winger Ze Roberto.
After seven rounds, Bruno Labbadia's men top Bayer Leverkusen on goal difference with both on 17 points.
Bayer won 1-0 at Cologne in an earlier kick off with a late goal from Simon Rolfes.
Champions VfL Wolfsburg also revived their title challenge with a 4-2 win at Hannover ahead of a midweek trip to Manchester United in the Champions League.
Schalke won 1-0 at Borussia Dortmund to move into third, four points behind the leading pair, while Werder Bremen are fourth, a further point back, after a 3-0 win over Mainz.
But most eyes were focused on the late clash at the HSV-Arena with Louis van Gaal's Bavarian giants arriving off the back of three straight victories.
Wingers Franck Ribery and Arjen Robben were included in the starting line up for the first time this season, while Hamburg were back to full strength after their shock German Cup exit to third flight Osnabruck.
Ribery and Robben both impressed early in the match, but Hamburg improved and Hans-Jorg Butt had to make a fine save to deny Jerome Boateng on the half hour mark.
From the corner, Joris Mathijsen tested Butt once again and the Bayern goalkeeper made another impressive stop.
In the second half, Butt was called into action to make further saves from Mathijsen and Petri.
The pressure was rewarded when former Bayenr stalwart Ze Roberto made a superb run before crossing to give Petric an easy chance in front of goal which he gratefully accepted.
Bayern slip to sixth on 11 points with the defeat as they battle to win back the Bundesliga title after last year's disappointments.