Juventus winger Douglas Costa has apologised but faces a lengthy ban after spitting in the face of Sassuolo's Federico Di Francesco during an Italian Serie A match.
The flash point came in second-half stoppage time as Juve saw out a 2-1 victory, with Cristiano Ronaldo scoring twice to get off the mark this season.
Sassuolo had just pulled a goal back through Khouma Babacar when Costa and Di Francesco squared up.
Brazilian winger Costa already looked to have lost his composure after aiming an elbow and a headbutt moments earlier but the worst was to come as he spat directly at Di Francesco from inches away.
Costa was sent off after the intervention of the video assistant referee.
Juventus coach Massimiliano Allegri admitted the behaviour was unacceptable and Costa later offered his mea culpa on Instagram.
"I would like to apologise to all Juventus fans for this misleading reaction in today's game. I also apologise to my team-mates, who are always with me in beautiful and bad moments," he wrote.
"It was a bad mistake, I am aware of it and I apologise to everyone for this. I make it clear that this isolated attitude does not correspond to what I have always shown in my career."
Now Costa could see the Italian authorities clamp down on his behaviour.
"Even if he was fouled, these episodes must not happen," Allegri told reporters.
"The only thing we have to avoid doing this year is rising to the provocation.
"We had the game where we wanted it but we started playing as individuals and not as a team."
Allegri added that Costa will face club sanctions.
"It's only right that he (Costa) is fined, and he certainly will be... I was surprised by his reaction," he said.
"We have suffered a goal, a red card and a suspension which will be long."