ARLINGTON -- A's starter Dallas Braden will undergo surgery on Monday to repair a torn capsule in his left shoulder, the club announced Wednesday.

The recovery time will be determined following the procedure, which is to be performed in New York by Mets medical director David Altchek, but the A's realize Braden's season is now in jeopardy.

"We're aware that it's a possibility he could be out for an extended period of time," said assistant general manager David Forst. "At the same time, it doesn't do anyone any good to say anything until we know for sure. Plenty of times, you get in there and it's not as bad as the MRI may have showed."

As a frame of reference, Altchek performed the same shoulder surgery on Mets lefty Johan Santana in September, and he has yet to return to action. Every case is different, though, so the A's are hoping their hurler faces a shorter rehab process.

Braden met with Altchek on Tuesday, marking his fourth doctor's appointment and third professional opinion since landing on the 15-day disabled list on April 18 with a stiff shoulder.

The A's southpaw had pitched two days prior, when he exited his third start of the season after five frames because of the discomfort. In those starts, he posted a 1-1 record and a 3.00 ERA, yielding 18 hits with 15 strikeouts and five walks in 18 innings of work.

Braden first met with Dr. Lewis Yocum on April 20, when he was told to simply rest and rehab to calm inflammation in his shoulder. But when the left-hander took to the field last week to play catch for the first time, he experienced discomfort again, leading to another visit with Yocum and a new MRI that revealed the damage.

Seeking another opinion based on the results, Braden flew to Florida on Monday to meet with renowned surgeon James Andrews before heading north for his appointment with Altchek, who was the only doctor out of the three who recommended surgery.

In Braden's stead, right-hander Tyson Ross is expected to continue filling the fifth spot in Oakland's rotation, where he's quietly posted a 2.51 ERA on the season while allowing just three earned runs in his past three starts combined. Those efforts have helped the A's starting staff to a Major League-leading 2.69 ERA through its first 37 games.

"This is disappointing for Dallas because we know he was hoping to avoid surgery," Forst said, "but from our standpoint, we have Tyson and we're very happy with the way he's performed. It cuts into our depth a little bit, but at this point, we're comfortable with the starters we have."

Braden, 27, has been the victim of numerous injuries throughout his eight-year professional career. This marks the third straight year during which he's spent time on the disabled list. He's also no stranger to shoulder surgery, having missed much of the 2006 campaign following a procedure to repair a humoral defect.

The news came just two days following the anniversary of Braden's perfect game against the Rays on Mother's Day.

"It's a tough day because he's such a competitor," said manager Bob Geren. "He's a good kid, and I hope the best for him, because he means a lot to the team and we'll miss him."