Cristiano Ronaldo scored his first two goals for Juventus as the Italian giants maintained their great start to the season.
Ronaldo, goalless in 320 minutes of play since his move from Real Madrid, broke his drought shortly after half-time.
The 33-year-old then finished off a quick counter-attack by hitting the bottom corner after 65 minutes.
Sassuolo pulled one back in added time via Khouma Babacar.
Diego Costa was dismissed after a video assistant referee intervention for spitting at Federico di Francesco, having aimed a headbutt at the same player and appeared to try to elbow him.
Ronaldo could have completed a hat-trick late on but missed two easy chances from inside the penalty area.
The win is Juventus’ fourth from four games this season.
Click below to see Ronaldo’s double.