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7/21/2013 8:01 P.M. ET

Surkamp likely candidate to start in twin bill

SAN FRANCISCO -- The Giants are expected to summon left-hander Eric Surkamp from Triple-A Fresno to start one of the games in Tuesday's doubleheader against the Cincinnati Reds.

Giants manager Bruce Bochy said after Sunday's 3-1 loss to the Arizona Diamondbacks that he wanted to discuss the issue further with his coaching staff before finalizing a decision. Left-hander Barry Zito will start the doubleheader's other game.

Surkamp made his most recent start last Thursday and will have received his regular four days of rest by Tuesday. By contrast, left-hander Mike Kickham, another candidate to get the start, pitched Saturday night and wouldn't have enough recovery time to face the Reds.

Surkamp, rated the No. 9 prospect within the organization by MLB.com, has progressed steadily since undergoing Tommy John elbow surgery last July 24. He's 2-0 with a 4.00 ERA in nine starts this year with Class A San Jose and Fresno. With Fresno only, Surkamp's 2-0 with a 4.79 ERA, a 1.65 WHIP (walks plus hits per inning pitched) and a .316 opponents' batting average in four starts.

Surkamp was a long-shot candidate for a spot in the Giants' starting rotation last year before his elbow problems materialized. He made six late-season starts for San Francisco in 2011, posting a 2-2 record and a 5.74 ERA.

A Cincinnati native, Surkamp would face his hometown team for the first time.

Affeldt goes on disabled list with groin strain

SAN FRANCISCO -- Giants left-hander Jeremy Affeldt's strained left groin could sideline him for as long as four to six weeks, manager Bruce Bochy announced Sunday.

Though Affeldt had endured inconsistency this season, his absence robs the Giants of one of their most versatile relievers. As Bochy pointed out, Affeldt's capable of pitching multiple innings and at different junctures of the game.

"It's too bad this happened, because he's an important part of the bullpen," Bochy said of Affeldt, who's 1-4 with a 3.51 ERA in 38 appearances.

The Giants recalled right-hander Jean Machi from Triple-A Fresno for the fourth time this season to fill the bullpen vacancy Affeldt created. Machi compiled a 2-0 record and a 3.58 ERA in 26 games during his previous Giants stints.

Affeldt, 34, went on the DL twice with left groin strains while pitching for Kansas City in 2005. He revealed that he had sensed some discomfort in his groin area for a few weeks but remained able to pitch, mainly because the nagging feeling didn't affect his delivery.

Affeldt didn't second-guess himself for continuing to perform, though he did say, "Sometimes being a tough guy doesn't work out."

That was the case in Saturday night's sixth inning against Arizona. After retiring Cliff Pennington on a fly ball for the inning's second out, Affeldt flung a 3-1 sinker to pinch-hitter A.J. Pollock and staggered off the mound in obvious pain, grabbing his injured area.

Affeldt, who has been prone to freak accidents, maintained his sense of humor by noting, "I got hurt on the field, which is comforting for me. It's better than getting out of the car and pulling it."

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.