Philadelphia general manager Ruben Amaro Jr. said the reliever will not need surgery to fix the problem, deemed a posterior rotator cuff strain.
Lidge will start the season on the disabled list. The NL East champions open at home Friday against Houston.
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"It's an issue obviously when you lose your closer," Amaro said. "It's not good news."
Phillies manager Charlie Manuel said prior to Tuesday night's exhibition game against Pittsburgh that Jose Contreras likely would begin as the team's closer. Setup man Ryan Madson is another option for Manuel.
Lidge had issues with his velocity during spring training. Last season, he was 1-1 with a 2.96 ERA while converting 27 saves in 32 chances.
"We knew something was going on in there," Amaro said. "We're just glad it's not a labrum. It doesn't need to be surgically repaired."
The Phillies enter the season with a strong rotation, but injuries are already taking a toll. All-Star second baseman Chase Utley, third baseman Placido Polanco and right fielder Domonic Brown all were banged up during spring training.
