Tampa Bay Rays ace left-hander Shane McClanahan (shoulder) scratched from scheduled start against Miami Marlins

MIAMI -- Tampa Bay Rays All-Star left-hander Shane McClanahan was a late scratch in his scheduled start against the Miami Marlins Tuesday because of left shoulder impingement, the team said.

The 25-year-old McClanahan (11-5, 2.20 ERA) has made 24 starts and emerged as one of the top pitchers in the major leagues this season. He will undergo further testing on Wednesday.

"Going into the game, something just didn't feel right," McClanahan said. "Just couldn't get loose. Can't put a finger on it."

McClanahan will undergo additional tests but is optimistic he won't deal with a lengthy absence.

"Didn't want to take the risk of jeopardizing the big picture for one or two starts," McClanahan said. "We're actually pretty optimistic about it. Don't think it's anything major."

Right-hander Shawn Armstrong replaced McClanahan against Miami, throwing three scoreless innings and allowing three hits in the 7-2 win.

The Associated Press contributed to this report.