PEORIA, Ariz. – A blister on Luis Mendoza's right middle finger means he'll begin the season on the disabled list. The Texas Rangers don't believe it's serious and expect Mendoza to start April 12 against Toronto, the first time the club needs a fifth starter this season.

He is scheduled to make a rehab start at Triple-A Oklahoma on April 7.

The blister bothered Mendoza during a bullpen session Wednesday, and the club decided to rest him and let it heal. He left his last start Sunday a little earlier than planned because the blister was starting to form.

"I don't expect it to be an issue past a week or so," general manager Jon Daniels said. "Just to be safe, he's not going to make his start on Friday. He's had it in past springs and once it peels off and heals, he hasn't had issues with it beyond that."

The Rangers have some experience with blisters. Brandon McCarthy had one on his right middle finger and missed nearly a month last season because of it.

Bullpen coming into focus: Right-hander Josh Rupe claimed a bullpen spot Wednesday, leaving Robinson Tejeda and Wes Littleton to compete for the final relief job. That decision could be made today. Tejeda might have the edge because he has no options left and Littleton does.

Right-hander Kameron Loe was sent to the minors, ending his chance to make the opening day roster.

Washington praised Rupe's progress this spring. The 25-year-old has allowed two earned runs in his last eight innings.

Briefly: Outfielder Josh Hamilton said he was taking some different anti-inflammatory medication for a slightly stiff back and it didn't sit well with him Tuesday. He was clearly feeling better Wednesday, when he hit a homer off Padres ace Jake Peavy.