It all started with a late tackle on Di Francesco in the 91st minute of Juventus' 2-1 win. Costa elbowed his opponent as he picked himself up, headbutted Di Francesco a few seconds later, and spit right in his face in one final confrontation.
Costa was initially cautioned for the headbutt before finally being sent off.
"I would like to apologize to all the Juventus fans for the over-the-top reaction in today's game," Costa wrote afterward on Instagram. "I also apologize to my teammates, who are always with me in good times and bad. It was ugly, I'm aware of that, and I apologize to everyone for it. I want to make it clear that this isolated episode does not reflect what I've always shown throughout my career."
Juventus manager Massimiliano Allegri confirmed after the match the club will discipline Costa.