Motsi Mabuse was in a backstage scrap after marking a contestant down, it's claimed.
The pro dancer, who has just been announced as the new Strictly Come Dancing judge, was allegedly confronted by the agent of one of the contestants on German show Let's Dance, which she also judges.
She gave German actress Sophia Thomalla a nine on her final dance, a point which cost her winning the show.
While Motsi, 38, explained it was because she danced barefoot, this answer was reportedly not good enough for Sophia's manager Alain Midzic.
Alain is said to have confronted her and her then husband Timo Kulczak in the lobby of the Savoy Hotel in Cologne in 2013 and things got "aggressive".
A source told The Sun : "Alain thought Motsi shouldn’t have marked Sophia down. He told her the remarks she made were ‘nonsense’.
"He was very aggressive, so Timo told him to shut up and gave him the middle finger. From there the situation escalated badly.”
The two men allegedly 'grappled' in the lobby and the police were called.
Motsi and Timo made an official complaint to police but no charges were brought, it's claimed.
Mirror Online has contacted reps for Alain Midzic and the BBC for comment.
Motsi was announced as Darcey Bussell's replacement earlier this week.
She started out as a professional dancer on Let's Dance, before she was upgraded to a judge in the fourth series, and has remained in the role for the past nine series.
It's been reported that the Strictly professionals are worried that new judge Motsi will give 'preferential treatment' to her sister Oti Mabuse , who is a popular member of the dancing cast.
They fear that there will be bias when it comes to dishing out scores and that Motsi will go easy on her younger sister, 28.
Motsi and Oti have already been in a similar position when Oti was a pro on the German show for two series and and has already experienced being judged by her sibling.
“Motsi is totally impartial,” said a source. “She will be scrupulously fair, as she always was with Oti on the German version.”
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