A slap from Bayern Munich star Sadio Mane left teammate Leroy Sane with a bloody lip after Tuesday’s defeat in the Champions League, according to The Athletic’s Raphael Honigstein.

After Bayern lost 3-0 in the first leg of their quarterfinal clash with Manchester City, the two engaged in an argument on the pitch before things turned physical, and teammates had to separate the wingers.

The incident resulted in Sane being treated for a bloodied lip, while Bayern are assessing the situation. A punishment is expected for Mane, who has struggled since joining the Bundesliga side last summer.

Mane has produced just 11 goals in 32 appearances during a debut season in Germany that was interrupted when he was sidelined with a serious calf injury.

Mane and Sane used to be rivals in the Premier League during their time with Liverpool and Manchester City, respectively, but it’s thought that there aren’t pre-existing issues between them, Honigstein adds.