ATLANTA -- Kris Medlen has been a valuable part of the Braves' rotation since he joined it in place of an injured Jair Jurrjens in May. There's a strong possibility the Braves will now need somebody to fill in for Medlen during the final two months of the season.

Medlen was forced to exit during the fifth inning of Wednesday night's 8-3 win over the Mets when he felt tightness in his right forearm and elbow. The Braves have revealed that he has an ulnar collateral injury. But before conceding the possibility that he will need to undergo Tommy John elbow ligament transplant surgery, they will wait to view the results of an MRI exam scheduled for Thursday.

"It's definitely scary, but you don't know anything until the MRI comes back," said Medlen, as he attempted to remain upbeat while talking to a group of reporters. "Anything is possible. It could come back with nothing. I don't know what to think or what to say."

If Medlen needs to undergo Tommy John surgery, he would likely be sidelined for at least a year. Even if his ligament is just slightly strained, he will be sidelined for a few weeks, and possibly longer.

"You never like to hear about an elbow with a pitcher," Braves third baseman Chipper Jones said. "All you've got to do is hope and pray for the best -- that the MRI comes back with something that doesn't require Tommy John."

While the Braves are already looking at all of their options, including the possibility of promoting the highly regarded Mike Minor, they will wait to see the results of the MRI exam before revealing who they could put in Medlen's spot of the rotation.

"They're talking about what they're going to do," Braves manager Bobby Cox said in reference to general manager Frank Wren and his top aides. "We'll see what the doctor says."

Medlen was forced to exit after throwing a 2-1 changeup to Mets shortstop Jose Reyes with two outs in the fifth inning. As he made his way back toward the pitching rubber, he had his right arm angled and positioned against his ribs.

"Nothing popped," Medlen said. "It was just awkward, kind of tight. It was like nothing I've ever felt before."

Cox had actually seen Medlen shake his right arm after throwing the previous pitch. After walking to the mound with assistant trainer Jim Lovell, he stopped the young hurler before he even attempted to test his arm with a warmup pitch.

"He couldn't throw another pitch, so obviously something popped in there," Cox said. "That's my opinion. I'm no doctor."

Medlen had allowed two earned runs on four hits before having to exit the fifth inning with one out. He has gone 5-0 with a 3.84 ERA in his 14 starts this year, and the Braves have won 13 of those games.

Cox indicated that he didn't think Kenshin Kawakami would have the endurance to fill Medlen's rotation spot. Kawakami has pitched just one inning since losing his spot in the rotation after beating the Tigers on June 26.

Minor, who was the seventh overall selection in the 2009 First-Year Player Draft, seems to be the most likely candidate. The 22-year-old left-hander has gone 4-1 with a 1.99 ERA in the five starts he has made since being promoted to Triple-A Gwinnett.

The Braves could have Minor skip his scheduled start on Thursday and be ready to fill Medlen's spot against the Astros in Houston on Monday.

As he made his way toward the clubhouse to talk to Medlen, former Braves pitcher John Smoltz said that his past experiences have led him to remain optimistic until the MRI exam is completed. Smoltz pitched for more than a year with a damaged elbow ligament before undergoing Tommy John surgery in 2000.

"There's always a chance," Smoltz said. "You've just got to hope for the best."