Two penalties after similar incidents gave Bayer Leverkusen a 2-1 win over Bayern Munich on Sunday and threw the Bundesliga title race wide open, with Borussia Dortmund ending the weekend on top.
Dortmund thrashed Cologne 6-1 on Saturday to take over at the summit but Bayern would have gone back to the top with a point ahead of the top two meeting in Munich in their next game on April 1. Instead Dortmund, last champions in 2012, lead by a point.
Joshua Kimmich put Bayern ahead in rainy Leverkusen against the run of play in the first half. But Exequiel Palacios levelled from the spot on 55 minutes after a video review showed Benjamin Pavard had felled Amine Adli - the forward had initially been booked for diving.
Adli then went down under Dayot Upamecano's sliding tackle and again was shown yellow for simulation. But again referee Tobias Stieler was called to the monitor and reversed his decision, Argentina's Palacios picking the same corner to make it 2-1 on 73.
Bayern captain Thomas Müller told DAZN: "I must say Leverkusen did very well, they were tricky to play against. We had lots of balls which we lost too quickly.
"Looking at the whole game, the defeat is unfortunately deserved. We are not in the Bundesliga where we should be."
Bayern are gunning for their 11th straight Bundesliga title and only eight games will remain after April's top-of-the-table clash, which follows the international break.
Union Berlin's Rani Khedira earlier fired his side up to third after his first goal for the club helped secure a 2-0 home win over sixth-placed Eintracht Frankfurt.
Freiburg - in fifth - are at Mainz in the late match knowing a win would put them above fourth-placed RB Leipzig, who lost at Bochum on Saturday, and level on points with Union.
Leverkusen and Bayern are the only two German sides to make it through to the quarter-finals of European competition this season and their good recent form prompted an intriguing contest.
Eighth-placed Leverkusen, bossed by former Bayern midfielder Xabi Alonso, made a good start with a few half chances but were soon made to pay for their profligacy.
Kimmich struck his fourth league goal of the season via a deflection on 22 minutes following Leon Goretzka's cutback. It was Bayern's only shot on target in the first half
Bayern coach Julian Nagelsmann - who shuffled his pack significantly against Leverkusen - has lamented a "mole" who has leaked his tactical plans but said he believed it was not a player.
Leverkusen looked like they had read the plans given they bettered the visitors in almost all statistics and turned the game around with two strikingly similar penalty incidents.
The referee laughed and shook hands with Adli after having to rescind his second yellow card, but the Bayern hierarchy in the stands were stony-faced in contrast.
Bayern substitute Jamal Musiala fired just wide after showing off his silky skills at 1-1 and Bayern had a plethora of chances late on from the likes of Serge Gnabry and Matthijs de Ligt, but ended up with their third loss of the Bundesliga cmapaign.
Leverkusen's Robert Andrich said: "We changed our matchplan a little bit. It gave us more options. We won lots of tackles."
Dead-ball specialists Union, who have never been in the Champions League, struck in the second half when Khedira - captain for the day and being watched by brother Sami - stabbed in following a corner.
Kevin Behrens nutmegged Kevin Trapp to make it 2-0 on 75 minutes.
