Bayer Leverkusen blew the chance to go top of 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.
Third-placed RB Leipzig can bridge the two-point gap and jump into first place if they win later at Stuttgart.
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 and Frankfurt grabbed the winner when Japan midfielder Daichi Kamada put in a cross which Leverkusen 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 notched 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.
- 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 tapping 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 Schmid had a goal ruled offside.
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.
- Winless in 30 league games -
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 first leg of the Champions League last 16 next month, earned their first win in five league games with a 1-0 victory at Arminia Bielefeld.
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.
Bottom side Schalke are now 30 games without a win -- one short of the Bundesliga record -- after a 3-0 defeat away to Hertha Berlin.
Former Tottenham manager Christian Gross, installed as Schalke's fourth head coach this season, got off to a losing start as Arsenal loanee Matteo Guendouzi, Colombia striker Jhon Cordoba and his replacement, Poland forward Krzysztof Piatek, scored for Hertha.
Having netted two minutes after coming off the bench, Piatek had a second late goal ruled offside.