BEREA, Ohio >> Joe Thomas screamed and crumpled to the ground in pain. In an instant, a routine morning practice for the Browns turned much more significant.

The team is awaiting further medical tests on Thomas, their ultra-durable Pro Bowl left offensive tackle who injured his right leg Monday when massive rookie nose tackle Danny Shelton inadvertently rolled up on it during an 11-on-11 drill.

Thomas, who has never missed a play in his eight-year NFL career, yelled as his leg was struck from behind by the 339-pound Shelton. Thomas limped off and was examined by head trainer Joe Sheehan, who tested the stability in the lineman’s knee and looked at his calf area and ankle.

As Thomas lay on the ground, quarterback Josh McCown came over to check on his condition.

The sight of Thomas going down left a few teammates shaken.

“There’s cornerstone guys that you really need out there,” linebacker Paul Kruger said, “and Joe has been an effective player for a long time. You want to take care of those guys and make sure they’re healthy and I’m hoping everything is OK.”

Browns coach Mike Pettine doesn’t think the injury is serious, but said Thomas would undergo more “normal” testing.

While the Browns were finishing up practice, Thomas walked to the team’s facility under his own power — and without limping — and didn’t seem overly concerned about the injury.

The Browns have been besieged by injuries throughout camp, but no player means more than Thomas, the first lineman in NFL history to make the Pro Bowl in each of his first eight seasons. Thomas has played 7,917 consecutive snaps since the first start of his rookie season in 2007.

After leaving the field, right guard John Greco checked on Thomas as he was being looked at by medical personnel.

“I just tried to go in there and show support because he’s a friend, a teammate and I just kind of gave him a (high) five and said, ‘Hey, I hope everything’s OK,'” Greco said. “I didn’t want to sit there and ask him 100 questions, just to show him that I’ve got his back, and I’m sure he’s OK.”

The Browns open their exhibition season at home Thursday night against Washington. If Thomas can’t play, versatile rookie lineman Cam Erving could see time with Cleveland’s starting offense.

Erving, a first-round pick from Florida State, is confident Thomas will bounce back quickly.

“Joe’s fine,” Erving said. “Joe’s got a great track record. He hasn’t missed a game. He hasn’t missed a snap since he’s been in the league, so he’s somebody that I don’t worry about. You’ve just got to take extra precaution because he’s such a great player and he’s such a durable guy.”

Thomas has started 128 straight games since the Browns selected him with the No. 3 overall pick in 2007 and plugged him into their lineup. He’s a five-time All-Pro.

NOTES: CB Justin Gilbert has been getting reps returning kickoffs and will do so against the Redskins. “He’ll be part of that mix,” Pettine said.” Gilbert returned kicks at Oklahoma State. … WR Brian Hartline came up gimpy following the final play of practice, but appeared to be OK. … WRs Dwayne Bowe, Terrelle Pryor and rookie RB Duke Johnson remain sidelined with injuries. Johnson has already been ruled out of the preseason opener. … Browns RB Shaun Draughn said he injured his left thumb early in Friday’s scrimmage in Columbus, but kept playing. He does not know how long he’ll be out. … Rookie LB Mike Reilly dislocated a finger during practice, but returned. … Offensive coordinator John DeFilippo was not happy with his unit and huddled his players for some choice words after QB Johnny Manziel threw an interception.