Galatasaray defender Marcao is facing a lengthy ban for headbutting and punching team-mate Kerem Akturkoglu during a Super Lig victory at Giresunspor on Monday.
Brazilian centre-back Marcao confronted winger Akturkoglu during the second half of the game when his side were leading 2-0.
An enraged Marcao headbutted Akturkoglu before swinging for the 22-year-old Turkey international twice.
Marcao was given his marching orders following a VAR review and could reportedly face a 10-match ban.
Galatasaray manager Fatih Terim said after his side saw out a 2-0 win: "The club will do what is necessary in their own way.
"Marcao will apologise to Kerem and the rest of the team for his behaviour."