The win sees Hamburg stay fifth on 30 points, four behind joint leaders Hoffenheim and Bayern Munich. Wolfsburg are now sixth, four points behind Martin Jol's men.

Croatian international Petric opened the scoring for Hamburg on the quarter-hour mark, heading home Marcell Jansen's cross at the far post to make it 2-0 after 31 minutes as Cologne failed to adequately deal with a Hamburg corner.

Milivoje Novakovic pulled one back for Cologne seven minutes from time, striking a well-placed shot from 11 meters for his 10th goal of the season, but Hamburg held on for the win.

Cologne have now lost four games in a row but are still safe in mid-table, seven points above the relegation zone.

Zvjezdan Misimovic was the hero for Wolfsburg, scoring from a free-kick on 63 minutes, just four minutes after Hanover's Jiri Stajner had cancelled out Cristian Zaccardo's first-half opener, which was beautifully set up by Misimovic.

Hanover were reduced to 10 men on 80 minutes when goalkeeper Florian Fromlowitz saw a straight red for a professional foul on Edin Dzeko.

With Hanover having used all their substitutes, midfielder Jan Rosenthal was forced to go into goal and, incredibly, he saved Dzeko's subsequent spot kick.

Saturday action

Bayer Leverkusen regrouped after a couple of defeats to win 3-1 at Borussia Moenchengladbach on Saturday to keep in touch with Bundesliga leaders TSG Hoffenheim and Bayern Munich.

Stefan Kiessling struck twice and fed Patrick Helmes for the other for Leverkusen, who are unbeaten against Moenchengladbach in 23 matches since the last defeat in 1994.

Leverkusen have 31 points, moving into third place ahead of Hertha Berlin, who remain on 30 after losing 1-0 at beleaguered Schalke 04, and Hamburg, who also have 30 points but sit one behind Hertha on goal difference.

Hoffenheim and Munich lead the way with 34 points each after Munich won their classy table-topper 2-1 from Luca Toni's injury time goal on Friday night. Promoted Hoffenheim remain top thanks to a superior goal difference.

Leverkusen topped the table just three weeks ago but then suffered a 2-1 loss at lowly Arminia Bielefeld and a 2-0 home defeat against Munich.

They rebounded on Saturday with Kiessling opening the scoring on a solo effort in the 15th minute. The forward got his second goal 12 minutes later on the counter and then played a neat one-two with Helmes in the 54th with Helmes firing home a low shot for a 3-0 lead.

Moenchengladbach managed no more than a consolation goal from teenager Toni Jantschke as they plunged to the bottom of the table.

"We are back on track now ... But we had to work hard for this victory," said Leverkusen coach Bruno Labbadia.

Schalke recover to beat fragile Hertha

Schalke won a match of midweek UEFA Cup losers against Hertha Berlin to move into sixth place with 26 points in an indifferent season, with Hertha too passive after winning their previous four league matches.

It took Schalke until the 64th minute to break the deadlock. Veteran Gerald Asamoah headed into the empty net after Hertha goalkeeper Jaroslav Drobny sailed past Jefferson Farfan's cross from the left wing.

"We didn't invest enough into this game," admitted Hertha captain Arne Friedrich, while Schalke sports director Andreas Mueller praised "super Asamoah" who gave Mueller and coach Fred Ruetten a breather.

The 2007 champions VfB Stuttgart got their second win in a row under new coach Markus Babbel, 3-0 at lowly Energie Cottbus from Roberto Hilbert, Jan Simak and Sami Khedira.

See-saw season continues for Frankfurt

Midtable Eintracht Frankfurt continued their seesaw ride by beating VfL Bochum 4-0 after a 5-0 loss in Bremen, a 4-0 win over Hanover and a 4-0 defeat at Borussia Dortmund.

Bochum were down to 10 men after five minutes when goalkeeper Daniel Fernandez was sent off for felling Martin Fenin. Nikos Liberopoulos converted the ensuing penalty and also headed Frankfurt's second, with Markus Steinhoefer and Marco Russ completing the rout.

SC Karlsruhe left the drop zone with their first win in eight matches, 1-0 against Werder Bremen from Stefan Buck's late strike. Claudio Pizarro hit the post for Bremen 20 seconds into the game and was sent off in the final minute.

There were no goals in the Bielefeld versus Dortmund game.