PITTSBURGH (AP) — Cleveland Browns star running back Nick Chubb was carted off the field with a serious left knee injury against the Pittsburgh Steelers. Pittsburgh safety Minkah Fitzpatrick came in low for a tackle at the end of a 5-yard run early in the second quarter and delivered a hit to Chubb’s legs. Chubb’s knee buckled underneath him. After the play, a teammate grabbed Chubb’s hand to try to help him to his feet, and Chubb shook his head while clutching his left knee. He undid his chinstrap and rolled over onto his side. Chubb suffered a major injury to the same knee in 2015 while in college at Georgia — a dislocation with three torn ligaments.