SAN FRANCISCO -- The Giants called up Yusmeiro Petit from Triple-A Fresno before Friday's game against the Dodgers, giving the club a 13-man bullpen to work with.

The 27-year-old right-hander signed with the Giants as a Minor League free agent before this season and had spent the entire 2012 season in Fresno's starting rotation, going 7-7 with a 3.46 ERA. Petit last appeared in the Majors with the D-backs in 2009 and will provide another option in a deep but recently worn out relief corps.

"He can help give us innings," manager Bruce Bochy said. "He's more of a long guy because he's been starting, and he gives us coverage there if something happens. He can start or eat some innings there. He's got experience there, and he was throwing the ball well down in Fresno. We just wanted to give ourselves more coverage."

Nady's hamstring strain mild, but return uncertain

SAN FRANCISCO -- An MRI on Xavier Nady's injured left hamstring confirmed a strain, Giants manager Bruce Bochy said before Friday's game against the Dodgers.

Nady sustained the injury while attempting to catch a seventh-inning double against the D-backs on Wednesday, and Bochy said that though the injury isn't serious, the Giants remain unsure how long the 33-year-old veteran will be sidelined.

"It's hard to say how long," Bochy said. "It could be four to five days or it could be seven to 10 days. He feels that he can be sooner than later. He's done it before, and he said it feels a lot better than the last time he did it."

Nady had briefly become the go-to option in left field after joining the team from Triple-A Fresno, and Bochy said Wednesday the team will need to "get creative" to replace Nady in left field, starting with Brandon Belt getting the start there Friday.

Belt gets start in left field for Giants

SAN FRANCISCO -- Brandon Belt shifted from first base to left field for Friday's game against the Dodgers as the Giants looked for ways to compensate for Xavier Nady's injured hamstring and keep Belt's surging bat in the lineup.

"With Nady going down, this move allows us to get both Belt and [Buster] Posey in there," manager Bruce Bochy said before Friday's game. "Buster is going to catch a day game tomorrow, and I knew he'd play first today and I didn't want to sit Belt. I look forward to him going out there."

Bochy talked with Belt about the possibility after Wednesday's game against the D-backs, and though he hasn't practiced any fly balls in the outfield since Spring Training, Belt headed there with confidence in his defensive play.

"I feel comfortable out there," Belt said. "Obviously I'm not going to be climbing any walls and robbing home runs, but I feel like I can do a good enough job to help us win."

Belt leads all Major League players with a .371 average since Aug. 1, with 11 runs and 13 RBIs in that span. He got some tips from outfielder Justin Christian and first-base coach Roberto Kelly about how to man left field at AT&T Park.

"I can definitely gain some confidence from this move," Belt said. "The coaches have enough confidence in me to be in the lineup every day and know that I can contribute. I think it'll help me play better, too."

The Giants also activated Christian from the disabled list before Friday's game to give the team further depth in the outfield.