According to sources close to Bentley the injury was a potentially season-ending injury to his patellar tendon, ESPN.com's John Clayton reported. Bentley was in the process of getting an MRI to determine whether it is a partial or total tear.
Bentley got tangled in a pile of players as he was blocking on a running play for Reuben Droughns.
Bentley screamed, "No," before remaining on his knees as the Browns moved their scrimmage up the field so the 6-foot-2, 309-pounder could be attended to. He stayed on the ground in a seated position for several minutes before Cleveland's medical staff immobilized his left knee and carted him to the locker room.
Crennel had his players only in shoulder pads for the two-hour morning workout, hoping that staying out of full pads on Day 2 of camp would help them avoid injuries.
The Browns have been cursed with serious injuries the past few seasons. On Thursday, tight end Kellen Winslow practiced for the first time in two years in pads after missing the past two seasons with leg injuries.
Bentley, a two-time Pro Bowler who was regarded as one of the offseason's premier unrestricted free agents, signed a six-year, $36 million deal in March that included $12.5 million in guaranteed money.