Arjen Robben scored a hat-trick as Bayern followed up their 7-1 win over Hoffenheim and 7-0 Champions League rout of Basle with another thumping victory.

Thomas Muller made it 1-0 in the ninth minute before Robben opened his account three minutes later and then added another from the penalty spot in the 19th minute.

Mario Gomez converted another penalty to make it 4-0 in the 50th minute before Toni Kroos struck a minute later and Robben completed his treble with another penalty midway through the second period.

The win kept Bayern five points behind Dortmund, while Hertha slipped to second bottom.

Dortmund earlier extended their unbeaten run to a Bundesliga record 20 games with a 1-0 win over Werder Bremen thanks to Shinji Kagawa's early goal.

Borussia Monchengladbach strengthened their hold on third place with a 2-1 win at Bayer Leverkusen.

Marco Reus put Gladbach ahead after seven minutes only for Stefan Kiessling to equalise in the 75th minute.

But Igor de Camargo struck two minutes from time to end the visitors' three-game winless streak.

At the other end of the table, Freiburg and Augsburg both claimed important wins in the fight for survival.

Freiburg won 3-1 at fellow strugglers Hamburg, while Augsburg were 2-1 winners over Mainz.

Johannes Flum's deflected effort gave Freiburg the lead after 20 minutes and Daniel Caligiuri doubled the advantage two minutes before the break.

Cedrick Makiadi made it three after 73 minutes before Ivo Ilicevic pulled a goal back for Hamburg two minutes later.

Augsburg came from a goal down to see off Mainz thanks to Sebastian Langkamp's second-half strike.

Sami Allagui put Mainz ahead after 36 minutes, but the home side equalised through Koo Ja-cheol in the 43rd minute before Langkamp clinched the points for his side six minutes into the second period.

Augsburg now sit one point and one place above third bottom Freiburg.

Elsewhere, Patrick Helmes scored twice as Wolfsburg won 3-1 at Nurnburg.

Daniel Didavi gave the home side the lead after nine minutes, but Mario Mandzukic equalised in the 15th minute.

Helmes put the Wolves ahead after 24 minutes and finished the game with his second goal eight minutes into the second period.