Bayern Munich reasserted their title credentials with a 3-0 home victory over third-placed Schalke.
Nearest pursuers Hamburg had cut the gap at the top to three points after a 1-0 win over Wolfsburg on Saturday.
But Bayern's lead is now back to six points after the champions produced a clinical second half performance.
Following a tight first period, Bayern made the breakthrough on 49 minutes courtesy of Hasan Salihamidzic.
Claudio Pizarro added a second goal on 56 minutes to leave Schalke with an uphill battle to retrieve anything from the game.
Any faltering hopes of a comeback were shot down a minute from time when substitute Roy Makaay sealed the 3-0 success.
Hertha Berlin lifted themselves up to sixth in the table after a 61st minute effort from Marko Pantelic saw off Arminia Bielefeld at home.