The Brazilian international's late antics took the limelight away from a Cristiano Ronaldo classic at the Juventus Stadium.
Costa, 28, took out Federico Di Francesco with a clumsy challenge in stoppage time, before elbowing him as they got back onto their feet.
The referree let the game continue as Sassuolo were in possession - the 'Neroverdi' scored a consolation goal through Khouma Babacar.
Sassuolo pressed forward after the restart, which also restarted the altercation between Costa and Di Francesco, with the former headbutting the Italian before spitting into his mouth from close range.
Douglas Costa was shown a red card after the clash was viewed by VAR, and the former Bayern Munich star could face more than three games on the sidelines.
16 de septiembre de 2018