Hoffenheim surged three points clear with a 3-1 win at Cologne in the Bundesliga on Saturday, while Franck Ribery scored for the sixth league game in succession to help Bayern Munich beat Energie Cottbus 4-1.
Hoffenheim, the village team with multi-millionaire backing, went ahead through Demba Ba and clinched victory as Vedad Ibisevic struck his 15th and 16th goals of the season.
It was enough to take them back to the top ahead of Bayer Leverkusen, who suffered a surprise 2-1 defeat away to Arminia Bielefeld.
With 14 games of the Bundesliga season played, and three to go before the long break, Hoffenheim lead with 31 points, followed by Leverkusen on 28.
Bayern are third, also on 28, after French midfielder Ribery sparked a revival at home to Cottbus with a terrific free kick.
The other Bayern goals, on a snowy afternoon in Bavaria, came from Martin Demichelis, Miroslav Klose and Luca Toni.
Hoffenheim coach Ralf Rangnick has dismissed title talk in the club's first Bundesliga season but if they keep winning tricky matches like this there will be no reason for modesty.
They were short of their flowing best against Cologne, but won an entertaining scrap thanks to superior finishing.
The opening goal was a neat strike, in off the far post, after Ba's well timed run had beaten the offside trap.
Both sides had a player sent off before Hoffenheim doubled their lead via Ibisevic from close range. Portuguese midfielder Petit got one back before Ibisevic supplied the finishing touch.
They got full value for the win as Leverkusen's patchy form continued with defeat in Bielefeld.
Artur Wichniarek cracked in the first and Daniel Halfar struck on the rebound for the second. Patrick Helmes got one back and very nearly bagged an equaliser when his venomous low free kick brought a fine diving save from the keeper.
While Hoffenheim can be delighted with that result, they might get nervous at the manner of Bayern's win over Cottbus.
This was Bayern's most convincing display yet under Juergen Klinsmann, even if they fell behind to an Ervin Skela free kick.
The setback brought out the best in Bayern, as they rattled in four goals in 30 minutes either side of halftime to make up for last week's 2-2 draw at Borussia Moenchengladbach.
Ribery's exquisite free kick from 20 metres brought them level and Demichelis had them in front before the end of the first half with a flick header from a Massimo Oddo cross.
Ribery then set up Klose to head in the third and Toni volleyed in from a free kick to round off the scoring.