NHL star Zdeno Chara beat the hell out of his opponent so badly during an on-ice scrap on Thursday ... the dude needed seven stitches to stop the bleeding.
The fight all went down during the Islanders' game against the Predators ... when Chara began throwing haymakers at Yakov Trenin after the Nashville center had hit one of Chara's teammates.
You can see in footage of the play, 6-foot-9 Chara pulled Trenin's jersey over his head -- and then whaled on him with a violent flurry of punches.