Borussia Dortmund slipped back to the bottom of the Bundesliga despite picking up a point in their goalless draw at Bayer Leverkusen.
A Nils Petersen hat-trick helped Freiburg come from behind to beat Eintracht Frankfurt 4-1.
Cardiff have agreed to sell Norwegian midfielder Mats Daehli to Freiburg in January.
Hoffenheim brought a spectacular end to their 2014 with a 5-0 Bundesliga victory at Hertha Berlin on Sunday.
Freiburg let a two-goal lead slip to draw 2-2 against Hannover and remain rooted to the foot of the Bundesliga.
Former Germany forward Mike Hanke has retired at the age of 31, saying he has lost his appetite for the game.
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