Leroy Sane was spotted appearing to hide his lower lip as Bayern Munich touched down in Germany following the team's 3-0 Champions League defeat at the hands of Manchester City.
The German forward is said to have been punched by team-mate Sadio Mane in a dressing room altercation that took place after the final whistle.
With a baseball cap pulled over his brow, the player – who had presented City with the most problems on the night, but failed to find the back of the net – drew in his lower lip as if to hide any injury he might have picked up after coming to blows with his team-mate.