SAN DIEGO -- While John Thomson and the Braves aren't quite sure about the significance of his injury, there's obvious concern that the right-handed starter could be absent for more than just a start or two.

Thomson was forced to leave Monday night's start against the Padres at PETCO Park because of what the Braves are calling a strained flexor tendon in his right middle finger. His status will be better known when he returns to Atlanta to visit a hand specialist.

"I don't know what's going to happen," a dejected Thomson said. "I can't squeeze anything right now."

After he released a 1-0 fastball to Mark Loretta, Thomson's finger popped loud enough for first baseman Adam LaRoche to hear it. Immediately, the veteran hurler balled over in pain and was quickly assisted by head athletic trainer Jeff Porter and manager Bobby Cox.

"It kind of worries me, something like that," Cox said. "That's what you throw with. I don't see him making his next start."

If Thomson were to miss just one start, it would likely be a relief to him. Although X-rays showed that there wasn't a fracture, he knows there could be some type of tear that would force him to miss a significant amount of time.

"I'm frustrated because I have no idea how long I'm going to be out," said Thomson, who is 11-3 with a 2.85 ERA since last year's All-Star break. "I have no idea and that's the most frustrating part."

Thomson's next scheduled start was set for Sunday afternoon at Fenway Park. Because there is a day off on Thursday, the rotation could be fixed and John Smoltz, who is scheduled to pitch Tuesday, would start Sunday's game on regular rest.

That could be altered if Mike Hampton, who exited Saturday's game in the third inning with tightness in his left forearm, is unable to make his start on Friday. But all indications are that the veteran southpaw will be fine.

Thomson will visit Dr. Gary Lourie, a hand specialist located in Atlanta on Tuesday or Wednesday. His flight from San Diego to Atlanta won't land until 8 p.m. ET on Tuesday night.