Two goals from Andre Schuerrle helped Mainz move provisionally back into second place in the Bundesliga with a 4-2 win at St. Pauli on Saturday.
Mainz is now 10 points behind Borussia Dortmund, which lost 1-0 to Eintracht Frankfurt when Fanis Gekas scored a late winner.
Going into the winter break, third-place Bayer Leverkusen can overtake Mainz if it beats Freiburg at home on Sunday.
Poor defending presented Andre Schuerrle with both his goals. The first came in the 11th when he had an easy tap-in after the ball was played across goal by Adam Szalai, and the 20-year-old scored again in the 28th when he was in the right place to capitalize on an effort from Malik Fathi.
St. Pauli fought back into the game in the 33rd with a penalty by Matthias Lehmann, and the home side was lucky not to concede a spot kick of its own when Marius Ebbers appeared to handle the ball in the area.
Szalai restored Mainz's two-goal advantage at the end of the first half when he cushioned a cross from Christan Fuchs over goalkeeper Mathias Hain into the net.
Lehmann gave St. Pauli renewed hope when he scored again after the ball was teed up by Gerald Asamoah. Lehmann's spectacular dipping effort was helped by a kind deflection from Mainz defender Nikolce Noveski, before Marco Caligiuri made the game safe for Mainz.
Dortmund's first defeat away from home - and second overall of the season - leaves it one point short of the record 44 at the halfway stage set by Bayern Munich in the 2005-06 season.
Gekas - the league's top scorer with 14 goals - scored with three minutes remaining when he was set up by Martin Fenin and blasted the ball into the roof of the net from 13 meters (yards).
Ricardo Clark made his first start of the season for Eintracht Frankfurt and the American twice went close for his side in the first half.
However, the best chance fell to Dortmund's Lucas Barrios. A great long pass from Nuri Sahin left him with just the goalkeeper to beat but the striker hit the ball well over the bar at the end of the half.
Dortmund appeared tired after its efforts in the Europa League midweek against Sevilla and Gekas was causing it plenty of problems in defense.
Coach Juergen Klopp was becoming increasingly animated on the sideline and he brought on striker Robert Lewandowski for midfielder Kevin Grosskreutz with 17 minutes to go.
Barrios went close again from a corner late in the game before Gekas scored.
Elsewhere, Raul Gonzalez scored a hat trick for Schalke in a 3-0 home win over Cologne.
The Spaniard signaled his intent early on when he headed Jefferson Farfan's corner into the arms of Faryd Mondragon. The 39-year-old goalkeeper was likely playing his last game for Cologne before an expected move to MLS side Philadelphia Union.
Raul got his first goal when he headed in a cross from Ivan Rakitic after 30 minutes following a mistake from Cologne defender Christopher Schorch.
His second came early in the second half when the ball fell kindly for him to volley it past Mondragon following a poorly defended cross from Farfan, and the 33-year-old completed his hat trick with another header with three minutes remaining. It brings the striker's season total to nine goals.
"I'm happy to have scored the goals, happy with the victory," Raul said. "We now have to keep up this level for the second half of the season."
Visiting Kaiserslautern beat Werder Bremen 2-1 with two goals from Srdjan Lakic, with both sides having a player sent off.
The Croatian scored the season's quickest goal so far after just 23 seconds when he headed in a cross from Christian Tiffert on the right wing.
Bremen equalized through a penalty from Aaron Hunt in the 34th after Mathias Abel brought the hardworking Marko Marin down in the penalty area.
Kaiserslautern regained its advantage early in the second half when Lakic poked the ball past goalkeeper Tim Wiese for his 11th goal of the season after he was set up by Ivo Ilicevic as slippery conditions hampered Werder's attempts to defend.
Alexander Bugera was sent off for the visitors, before Sandro Wagner earned a red card for fouling Tiffert late in the game.
Steve McClaren's Wolfsburg remains winless in six games after it fought back to earn a 2-2 draw at home to Hoffenheim.
Two goals from Luiz Gustavo and Gyfli Thor Sigurdsson gave Hoffenheim a deserved lead at halftime, but Diego scored with 15 minutes remaining when the Brazilian met a cross from compatriot Grafite and Edin Dzeko netted the equalizer in the 90th minute.
"We showed what we are capable of," McClaren said.
Hannover's fine run of five victories in a row - a club record - was ended when it lost 3-1 in Nuremberg.
An own goal from Steven Cherundolo gave Nuremberg the lead in the home side's first attack after 28 minutes. The American was unlucky to see Ilkay Guendogan's rebound deflect off his foot into his own net.
Nuremberg captain Andreas Wolf added another from close range when the ball fell to him after a scramble following a corner.
Hannover scored a penalty through Sergio Pinto with 15 minutes remaining, but the home side restored its advantage with a header from Julian Schieber.
