BOSTON -- For the fifth time this season, the Red Sox recalled right-hander Clayton Mortensen from Triple-A Pawtucket. The transaction took place before Wednesday afternoon's game against the Rangers, as Vicente Padilla was placed on the 15-day disabled list with right arm soreness.

"Padilla has a little soreness in his bicep," Red Sox manager Bobby Valentine said. "He could probably pitch on Friday, but we just aren't willing to take the chance of going short these next couple of days. It's not fair to the guys who are out there, and it could put us in a real bind."

Valentine held Padilla out of action against the Rangers on Monday and Tuesday after he gave up two home runs while not retiring a batter on Sunday. In that game, Padilla's velocity was noticeably down.

Mortensen was the player the Red Sox got from the Rockies for Marco Scutaro. He has turned out to be a valuable acquisition, posting a 1.17 ERA over 10 outings.

"Well, let's not jinx him, but he's risen to the occasion," Valentine said. "And he's thrown as well in Triple-A. It's not like he's just getting lucky. He's a pretty good pitcher. He throws different pitches, and he says he's ready to go."

To this point, Mortensen has been used mostly as a long reliever. Will Valentine start using him in some more high-leverage situations?

"You know, I hope there's only important situations for my bullpen pitchers to pitch in," Valentine said. "Then you could use everyone the way you draw it up. Often is the case that the guy who's available has to pitch a couple of innings when you don't really like it. One thing he adds is length, and that always has to be a factor when either using him or not using him. But yeah, I think he could pitch anywhere in the game."

Morales to join rotation, not clear who exits

BOSTON -- Though the circumstances still aren't entirely clear -- such as which pitcher he will replace -- lefty Franklin Morales will officially join Boston's rotation, most likely on Saturday or Sunday against the Indians.

Morales made a spot start in place of Josh Beckett on Sunday against the Twins, pitching six dominant innings in a 6-4 victory.

Manager Bobby Valentine's preference for a while has been to start Morales, but there haven't been any rotation vacancies.

Aaron Cook, who had struggled in three straight starts before pitching well in his most recent start, would be the most logical candidate to get bounced from the rotation. But Valentine said earlier this week that he will pitch in next week's three-game series in Baltimore.

Expect Valentine to reveal his pitching plans in more detail over the next couple of days.

Valentine: Ortiz feeling 'really good'

BOSTON -- Injured slugger David Ortiz reported to work on Wednesday feeling "really good," according to Red Sox manager Bobby Valentine. That piece of encouraging news came two days after Ortiz received a shot of marcaine for his ailing right Achilles.

Ortiz did some baserunning on the field before Wednesday's game and took batting practice indoors.

The Red Sox are 9-12 in the 21 games Ortiz has missed. There's a chance the DH could return at some point during the four-game series in Cleveland that starts Thursday.

"Probably, yeah, if everything goes well," Ortiz said. "I don't have a time set, but I'm getting closer."

With lefty Matt Harrison pitching for the Rangers on Wednesday, Ryan Lavarnway was Boston's designated hitter. The DH has been a revolving spot since Ortiz went down.