Dortmund maintain lead, Bayern held
Hertha Berlin succumbed to their sixth straight defeat in 2012, although there were plenty of positive signs for their new coach Otto Rehhagel in a narrow 1-0 loss to league leaders Borussia Dortmund at the Olympiastadion.
Rehhagel takes over as Berlin coach on Sunday and he followed the game from his home in Essen, but apart from the result, he will have been encouraged with what he saw.
The home side, led on the touchline by Rene Tretschok and Ante Covic following the dismissal of Michael Skibbe last weekend, wasted numerous chances against the defending Bundesliga champions, who claimed a fifth successive victory thanks to Kevin Grosskreutz's 66th-minute goal.
Bayern Munich saw their title challenge suffer a setback as they were held to a 0-0 draw by struggling Freiburg.
It might have been even worse for Bayern as well with Freiburg having the better chances to win the game as they moved off the foot of the table with a well-earned point.
Borussia Monchengladbach kept up their unexpected title challenge with a 2-1 victory at Kaiserslautern.
Two goals in five first-half minutes from Patrick Hermann and Juan Arango put Gladbach in the driving seat, but a stunning strike from Leon Jessen gave Lucien Favre's side something to worry about in the second half.
But the visitors held on for the win, keeping them just three points adrift of Borussia Dortmund at the top of the table.
Werder Bremen won a dramatic northern Germany derby 3-1 to condemn Thorsten Fink to only his second defeat as coach of Hamburg.
Marko Marin, Tom Trybull and Marko Arnautovic scored the goals as Thomas Schaaf's side posted victory at the HSV-Arena.
Mladen Petric's goal, which made it 2-1 in the 76th minute, was mere consolation for the home side, who remain in the bottom half of the table while Bremen cement their hold on fifth place.
Tomas Pekhart grabbed the winner as Nurnberg dampened Cologne's carnival celebrations with a 2-1 defeat in a tense relegation battle at the Frankenstadion.
Alexander Esswein gave Dieter Hecking's side the lead in the 28th minute, but Milivoje Novakovic brought Cologne - whose city is in the midst of its annual festivities - level in the 66th minute.
Pekhart earned Nurnberg all three points five minutes from the end of the game to give them a crucial win which takes them seven points clear of the bottom three while leaving Cologne six points away from danger.
Bayer Leverkusen bounced back from their midweek Champions League disappointment by keeping up the pressure on fifth-placed Werder Bremen with a convincing 4-1 victory over Augsburg.
Stefan Kiessling was on target twice as Robin Dutt's side took all three points four days after losing at home to Barcelona.
Gonzalo Castro and Andre Schurrle were also on the scoresheet, with Koo Ja Cheol's 50th-minute having given Augsburg hope for only 10 minutes.