Hamburg  - Andrey Voronin bagged a hat-trick as Hertha Berlin defeated Energie Cottbus 3-1 away to open up a four-point lead at the top of the German Bundesliga on Saturday.

Champions Bayern Munich came from behind to beat visiting Hanover 5-1 and are one of four teams level on 42 points, four behind Hertha.

Hoffenheim who fought out a goalless draw with visiting Werder Bremen, are joint second with Bayern, while Wolfsburg are fourth thanks to a 1-0 win over Karlsruhe.

Hoffenheim and Bayern share the same goal difference and both have scored 49 goals, while Wolfsburg are also level on goal difference but have scored three fewer goals.

Meanwhile SV Hamburg slipped to fifth after slumping to a 4-1 defeat at Borussia Moenchengladbach who move off the bottom, leaving Karlsruhe to prop up the table.

Improving VfB Stuttgart climbed to sixth with a 2-1 win over Borussia Dortmund.

Cottbus took the lead against visiting Hertha when an Atan Cagdas free-kick after 20 minutes went through the legs of goalkeeper Jaroslav Drobny.

But Voronin, on loan from Liverpool, headed Hertha level in the 34th, and the Ukraine striker struck again from close range just before the break.

He completed a fine hat-trick with a minute remaining when he went past three players on a run into the penalty are before firing into the net for his 10th goal of the season.

Bayern, who had won only one league match in five this year and were dumped out of the German Cup by Bayer Leverkusen midweek, were without the injured Franck Ribery in midfield and Luca Toni up front against visiting Hanover.

It looked as if it might be another uncomfortable afternoon for Juergen Klinsmann's side when Jiri Stajner opened the scoring for Hanover in the 25th minute.

Stajner on the left cut inside Lucio who slipped on the turf and then struck a shot which left the diving Michael Rensing in goal with no chance.

However Bayern responded quickly with two free-kicks on the left by Bastian Schweinsteiger, the first headed in by Daniel van Buyten in the 20th and the second finding the head of Miroslav Klose five minutes later.

A third goal followed from Hamit Altintop in the 34th, Lukas Podolski headed a fourth in the 73rd and Martin Demichelis headed a fifth in the 89th to enable Bayern to run out easy winners.

"We played with patience against a compact Hanover team and after going behind, something that is almost symptomatic this season, the team did not lose its poise," Klinsmann said.

"I knew the team would be aggressive and put in a lot of running from the start. The goals were the logical consequence of the game. We didn't allow ourselves to be unsettled in any way."

Edin Szeko was again on target for Wolfsburg, notching his 12th of the season as the Wolves edged a nervous 1-0 win against Karlsruhe.

Hamburg's inconsistency away from home continued in a 4-1 humbling at struggling Moenchengladbach.

Rob Friend and Tobias Levels scored for Gladbach either side of a Mladen Petric goal, before Roel Brouwers and Marko Marin from the penalty spot completed the misery for Martin Jol's side after the break.

Hoffenheim striker Boubacar Sanogo - on loan from Werder Bremen - struck the post three times against visiting Werder as the two sides settled for a goalless draw, in marked contrast to Bremen's 5-4 defeat of Hoffenheim earlier in the season.

Stuttgart's Mario Gomez made it 14 league goals for the season when hit the winner against visiting Dortmund. Stuttgart took an early lead when a free-kick by Elson floated into the goal, but Nelson Valdez levelled after the interval for Dortmund.

On Friday, Schalke defeated Cologne 1-0, while on Sunday Bayer Leverkusen play Bochum, and Arminia Bielefeld entertain Eintracht Frankfurt. (dpa)