May 11, 2009 5:36 PM EST

Celtics center Kendrick Perkins strained his left shoulder late in the fourth quarter on Sunday night, an injury that concerns the team.

Perkins has a history of shoulder issues, which are a constant worry for Boston's medical staff.

"I'm not getting an MRI," Perkins said, despite comments from coach Doc Rivers to the contrary. "I'm cool. I'm going to play. It's good. It didn't pop out. There's nothing I can do about it. All I can do for it is time and rest in the offseason, but right now I have to step up."

Rivers was surprised to see Perkins ready to re-enter the game roughly two minutes after he left with the injury.

"I thought he was out for good," Rivers said. "All three times he's been injured, though, he's gone back into the game and then missed time after that. I thought it popped out. Eddie (Lacerte, trainer) grabbed me and said, 'You have to call a timeout.' I hope it's not that bad, but he'll have tests and we'll find out."

Via Boston Herald