ST. PETERSBURG, Fla. -- Tampa Bay Rays ace Shane McClanahan left Thursday night against the Kansas City Royals because of mid-back tightness.

Soon after reliever Kevin Kelly started warming up in the bullpen, Tampa Bay manager Kevin Cash and a trainer went to the mound with two outs in the fourth and the game tied at 2. After a discussion, McClanahan left the field.

The left-hander (11-1) was looking to become the first 12-game winner of the season. He allowed two runs, four hits and walked two during a 66-pitch outing.

Tampa Bay first baseman Yandy Díaz left in the fifth after stumbling to the ground between second and third running on Randy Arozarena's two-out single. He remained on the ground and was tagged out, but was able to walk off the field on his own. There was no immediate word on Diaz's injury.