The Associated Press

HOUSTON - Astros left-hander Andy Pettitte has a strained muscle in his left forearm and will be evaluated by team doctors in the next few days.

Pettitte left four innings into Wednesday night's game against the Chicago Cubs with discomfort in the forearm. He was clearly distressed by the end of the fourth, wincing in pain as he walked off the mound to end the inning.

He allowed one run and two hits in four innings with four strikeouts.

Team officials said Pettitte is considered day-to-day but probably will be able to make his scheduled June 4 start against Pittsburgh.

"Maybe it's just a muscle strain, but after I threw a pitch, it was grabbing me a little bit," Pettitte said after Wednesday night's game.

RED SOX: Trot Nixon went 0-for-3 with a walk and made two catches in right field in an extended spring training game Thursday.

Nixon went on Boston's disabled list with a mildly herniated disc in his lower back in spring training, then pulled a muscle in his right thigh.

"He ran at about 75 percent, and the word was that it was encouraging," Red Sox manager Terry Francona said in Boston, "but he's not (ready) yet."

Nixon is scheduled to be evaluated today and play again Saturday.

GIANTS: The Arizona Diamondbacks optioned right-hander Brian Bruney to Triple-A Tucson on Thursday and purchased the contract of another righty reliever, Aiken High product Scott Service.

Service, 37, was signed to the team's minor-league camp late in spring training but has been strong at Triple-A. He was 5-0 with eight saves and a 3.68 ERA in 21 appearances.

Service was 0-2 with a save in 18 games for Arizona last season.

"He had been setting up and closing in Tucson," manager Bob Brenly said. "We will probably use him the same way."

PADRES: The San Diego Padres placed pitcher Jake Peavy on the 15-day disabled list Thursday because of a strained tendon in his right forearm. The move was made retroactive to May 20.

Peavy, 4-2 with a 2.01 ERA in nine starts, was scheduled to start Saturday in Milwaukee. Dennis Tankersley will pitch in his place.

"This is more of a precaution than anything else," San Diego manager Bruce Bochy said.

Peavy complained of soreness in his forearm Wednesday after a bullpen session.

To fill Peavy's roster spot, San Diego called up right-handed pitcher Brian Sweeney.