Second-placed Bayer Leverkusen blew the chance to top the Bundesliga Saturday after stumbling to a 2-1 defeat at Eintracht Frankfurt following a second-half own goal by Edmond Tapsoba.
With leaders Bayern Munich at home to strugglers Mainz on Sunday, Leverkusen squandered the opportunity to reclaim first place as the Bundesliga returned from a two-week winter break.
Leverkusen also lost to Bayern by the same scoreline before Christmas.
"I have made my feelings clear in the dressing room," Leverkusen head coach Peter Bosz told Sky.
"We deserved to lose - Frankfurt had a better claim to the victory."
Leverkusen midfielder Nadiem Amiri scored with a deft back-heel flick to give the visitors the lead after only 10 minutes in Frankfurt.
The hosts drew level 12 minutes later when Amin Younes got in behind the defence to score.
Frankfurt grabbed the winner when Japan midfielder Daichi Kamada put in a cross, which Leverkusen's Burkina Faso defender Tapsoba turned into his own net.
Before kickoff, Frankfurt director Fredi Bobic confirmed reports his club are interested in Bayern's teenage striker Joshua Zirkzee, after selling Dutch forward Bas Dost to Brugge.
Zirkzee could back up Frankfurt's top-scorer Andre Silva, who has nine league goals this season.
"He is a good, young footballer with a lot of potential and we are looking for a player of his profile," said Fredi Bobic of Zirkzee.
Third-placed RB Leipzig can bridge the two-point gap and jump into first place if they win later at Stuttgart.
- Awoniyi shines -
Union Berlin rose to fourth - into the Champions League places for the first time in the club's history - after their 2-0 win at Werder Bremen.
Liverpool loanee Taiwo Awoniyi, who has scored in his last three league games, capped another impressive display with a goal and assist.
After Bremen lost the ball in their own half, the 23-year-old Nigeria international took advantage of a two-on-two situation by drawing the defence and passing to Sheraldo Becker, who fired home on 12 minutes.
Awoniyi doubled Union's lead on 28 minutes by punting the ball over the line, just out of the reach of Bremen goalkeeper Jiri Pavlenka.
Bremen had a penalty appeal turned down when a shot by Japan midfielder Yuya Osako clipped the hand of a Union defender, then Romano Schmidt had a goal ruled off side.
Hoffenheim lost both defender Kevin Akpoguma and Germany midfielder Sebastian Rudy with early leg injuries as they crashed to a 3-1 home defeat to Freiburg.
With the hosts struggling to reshuffle, Freiburg were 3-0 up at half-time thanks to a Baptiste Santamaria goal, a Vincenzo Grifo penalty and an own goal by Senegal defender Kasim Adams.
Hoffenheim scored a second-half consolation goal through Togo winger Ihlas Bebou.
Borussia Moenchengeladbach, who host Manchester City in the last 16, first leg, of the Champions League next month, earned their first win in five league games with a 1-0 win at Arminia Bielefeld.
Burly Swiss striker Breel Embolo netted the winning goal just after half-time when he held off a defender and fired home.
Mid-table Augsburg rebounded after back-to-back defeats with a 1-0 win at Cologne with Brazilian winger Iago netting the late winner.
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