CHICAGO -- The A's received a surprise spark last year in the form of a utility infielder.

Adam Rosales has since been sidelined as he recovers from right foot surgery, but the new guy in town is picking up right where Rosales left off.

Andy LaRoche, signed by the A's to a Minor League contract in late January, received his fifth start of the season on Tuesday, making his third start at shortstop, and entered the contest batting .417 in 12 at-bats.

LaRoche was handed the start, in part, because Cliff Pennington is dealing with an infection in the sweat gland under his left arm. But manager Bob Geren noted that plugging LaRoche in the lineup these days has been an easy choice.

"When a guy is swinging the bat well," he said, "we'll find ways to get him in there."

LaRoche is relishing the opportunity, especially after a Spring Training during which he wasn't even guaranteed a big league job.

"Honestly, I didn't know what my chances were," he said. "No one really knew me or the type of player I was, and I wanted to show I could play multiple positions."

With his bat doing most of the talking and his glove steadily progressing, LaRoche ultimately beat out Eric Sogard for the utility spot and represented the lone non-roster guy to make the team.

The 27-year-old LaRoche hit .206 with four home runs and 16 RBIs in 102 games with Pittsburgh last year. Fifty-two of his 58 starts were at third base, where he feels most comfortable. But he was drafted by the Dodgers as a shortstop, and it's there where he's been able to show off an arm that has always been strong, thanks to endless rounds of long toss with brothers Adam and Jeff and father Dave while growing up.

"I've always had a fairly above-average arm," he said. "My brothers were always the pitchers and I was always the catcher. I wanted to throw it as hard as them, so it kind of came natural [since] they we were blessed with those arms."

Rosales' looming return, expected in May, leaves LaRoche's future in limbo. For now, though, he has too much to worry about on the field to even start thinking about next month's possibilities.

"Obviously, I'd much rather be playing every day, but the fact that there are four different positions out there that they can have me play, it's nice knowing there are opportunities for me to give guys days off," he said. "I still have a lot of work to do, a long way to go, but I feel like I can go out to any one position and hold my own. Hopefully, no one can tell it's a third baseman out there."

"He's been great," Pennington said. "He's playing with a lot of confidence right now."

Pennington limited by sweat gland infection

CHICAGO -- Cliff Pennington was held out of Tuesday's lineup against the White Sox for a second straight day with what A's manager Bob Geren described as an infection in the sweat gland under his left arm.

The Oakland shortstop has been deemed day-to-day but was doing "a lot better today," according to Geren. Pennington is experiencing soreness when swinging the bat, which explains his actions in Monday's contest, when he entered in the ninth to pinch-run for Andy LaRoche, who again received a start at shortstop on Tuesday.

In the 10th, with a runner on second base and two outs, Pennington bunted for the third out in an eventual 2-1 A's victory. Bunting, though odd in that situation, prevented him from experiencing too much discomfort.

The 26-year-old Pennington, who spent the majority of his offseason recovering from left shoulder surgery, is hitless in his last 10 at-bats and is 4-for-25 (.160) to start the season.

He's a career .223 hitter in April, though Geren's not too worried about his shortstop's offensive woes, especially considering the struggles up and down a lineup that entered Tuesday's contest with a combined .224 average.

"He's feeling good," the A's skipper said. "He's going to be fine."

Wuertz nearing start of Minor League rehab stint

CHICAGO -- A's right-hander Michael Wuertz, sidelined by a strained left hamstring, could potentially get back on the mound in a simulated game on Thursday and proceed with his rehab in a Minor League outing on Saturday, manager Bob Geren said.

Wuertz was placed on the disabled list on April 6, retroactive to April 2, after appearing in just one game -- an Opening Night stint that saw him toss one shutout inning with two strikeouts against Seattle.

It marks the second straight season in which the veteran reliever has experienced an early-season injury, as he missed the first month of 2010 because of a bout of shoulder tendinitis.

Upon Wuertz's return, the A's will likely option one of two long relievers to Triple-A Sacramento -- right-hander Tyson Ross or lefty Bobby Cramer. Ross, who was recalled when Wuertz was placed on the DL, made his season debut on Monday and pitched three scoreless innings while earning the win against the White Sox.

Cramer, meanwhile, has yet to appear in a game since April 1, when he walked one and struck out one in 1 2/3 shutout innings against the Mariners.

Worth noting

Coco Crisp experienced lower back tightness in Tuesday's game, forcing A's manager Bob Geren to use Josh Willingham as a pinch-hitter in the 10th inning. Geren said Crisp's chances of playing in Wednesday's finale are 50-50.