BEREA, Ohio -- D'Qwell Jackson's comeback may have suffered a setback.
Cleveland's starting inside linebacker, and one of the Browns' top players, left the practice field on Tuesday with a potentially serious injury.
Jackson, who missed the final 10 games last season with a torn pectoral muscle, walked dejectedly off the field during the evening session. As he approached the training facility, he favored his right side as he tried to open a door to the locker room.
He briefly left the field and returned to watch the end of practice without his pads and a towel wrapped around his neck. Jackson was consoled by several teammates who came to check on his condition.
Jackson did not speak to reporters, and the Browns had no immediate word on his condition.
The 26-year-old Jackson has been a steady player since being drafted by the Browns in 2006. He led the team with tackles in 2008, and was one of their stalwarts on defense before tearing his chest muscle last season when Pittsburgh tight end Heath Miller landed on him.
Before being put on injured reserve, Jackson had missed just five games in his first three years.
At one point, it appeared Jackson was set to hold out of camp in a contract dispute. Unhappy that the Browns would not give him a long-term contract -- the team tendered him a one-year, $1.76 million deal as a restricted free agent -- Jackson boycotted organized team activities and minicamp this spring.
He threatened to hold out from camp, but a recent trip to Africa with a close friend changed his perspective on things. On the trip, Jackson helped deliver school supplies and volunteered at a hospital.
"Probably the best experience of my life," he said last week.