"Gil Meche doesn't have an explanation. There's no biting pain in his shoulder, but renewed inflammation - diagnosed as bursitis - forced his return Saturday to the disabled list prior to the Royals' game against the Boston Red Sox.

"I don't why this keeps happening," he admitted. "We'll look into it and see what happens. I don't know. It sucks."

Veteran lefty Bruce Chen will replace Meche in the rotation Sunday when the Royals conclude a four-game weekend series at Fenway Park. Right-hander Brad Thompson will be the first alternative out of the bullpen.

"It was a coin flip between Chen and Thompson," manager Ned Yost said. "But (the Red Sox) have a few more lefty matchups, so we went with Bruce."

The Royals also recalled right-handed reliever Victor Marte from Class AAA Omaha to replace Meche on the active roster. Marte was in uniform for Saturday's game.

Meche's time on the disabled list is retroactive to Wednesday - the day after his last start. The tipping point came Friday when Meche experienced soreness in a pre-game throwing workout.

"It's achy, a tendinitis feeling," he said. "I played catch (Friday), and it didn't go well obviously. So, I'll miss a couple of starts and do what I've got to do to get it strong."

The Royals say Meche is already responding to treatment and believe he will be ready to pitch the day he is eligible for reinstatement: June 10 at Minnesota."