Borussia Moenchengladbach forward Marcus Thuram was sent off for spitting in an opponent's face during Saturday's 2-1 home defeat against Hoffenheim in the Bundesliga.
The France forward was shown a straight red card with 11 minutes left, which turned the game after the VAR spotted Thuram spitting at the visitors' defender Stefan Posch.
"You can't do something like that - that's hard to explain," Gladbach midfielder Christoph Kramer said, while team-mate Valentino Lazaro admitted Thuram's dismissal was what "broke us".
The incident happened just after Andrej Kramaric had equalised for the away side at Borussia Park.
Nine minutes after Thuram's dismissal, Tottenham loanee Ryan Sessegnon put Hoffenheim ahead when he tapped in a cross unmarked at the far post.
Gladbach, who face Manchester City in the last 16 of the Champions League in February, had gone ahead when their captain Lars Stindl converted a first-half penalty.
Having made his France debut in November, this was the first time Thuram - the son of 1998 World Cup winner Lilian Thuram - has been sent off for Gladbach in his two seasons in Germany.
It was the third red card of Thuram's career after he was sent off twice for former club Guingamp during the 2018/19 campaign.
Gladbach, winless in their last six games in all competitions, are now eighth in the league while Hoffenheim are up to 11th.
- Leipzig held -
With league leaders Bayer Leverkusen hosting European champions Bayern Munich later on Saturday, RB Leipzig missed the chance to go top after being held to a goalless draw at home by Cologne.
The point leaves Leipzig second in the table on goal difference, but level on 28 points with Leverkusen.
"That's annoying," Leipzig sports director Markus Kroesche said.
"We played well, but a bit of concentration was missing."
Despite bringing in Dutch veteran Huub Stevens on Friday as their third coach this season, Schalke are now 29 games without a win after their 1-0 defeat at home to Arminia Bielefeld.
Bielefeld, who are also in the bottom three, secured the points thanks to a header from captain Fabian Klos.
Schalke are now just two games from the unwanted league record of 31 winless games, set by Tasmania Berlin in 1965/66, and prime relegation candidates after 30 years in the Bundesliga.
"We can only get out of this if we all pull together," 67-year-old Stevens told Sky.
"The boys gave everything. What are we supposed to do? Give up? No! You always have to fight and keep going."
Elsewhere, having been recently playing fourth-tier football for their reserves, Werder Bremen's 19-year-old striker Eren Dinkci enjoyed a fairytale Bundesliga debut.
He scored their 90th-minute winner with a superb header to seal a 1-0 victory at Mainz just after coming off the bench.
Frankfurt ended their nine-match winless run with a 2-0 away win at Augsburg as Stefan Ilsanker netted late on after an own-goal by Raphael Framberger for the hosts in Bavaria.