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LOS ANGELES (Reuters) - The Los Angeles Angels could lose starting pitcher Joel Pineiro for as long as eight weeks after he strained a muscle in his left side while warming up for his Wednesday start against the Boston Red Sox.

Pineiro will be placed on the 15-day disabled list with a strained left oblique muscle he suffered while throwing in the bullpen before the game, the team said.

He likely will be replaced in the Angels' rotation by rookie Trevor Bell, who was optioned to Class AAA Salt Lake on Monday after the Angels swung a deal for Arizona Diamondbacks pitcher Dan Haren.

Pineiro was 10-7 with a 4.18 earned run average for the Angels, a distant second in the AL West behind the Texas Rangers.

Taking the right-hander's place on the mound Wednesday was reliever Scot Shields, who pitched 1 2/3 innings and gave up two runs in Boston's 7-3 victory.

The Angels later announced they added some more pitching depth by signing former Pirates and Giants pitcher Ryan Vogelsong and assigning him to Salt Lake.

Vogelsong had been pitching for the Phillies' AAA team before being released, following three seasons pitching for the Orix Buffaloes in Japan.

(Writing by Larry Fine in New York, Editing by Steve Ginsburg)