Pirates catcher Ryan Doumit needs an operation to repair a broken bone in his right wrist and will be out for at least eight to 10 weeks, an injury that significantly weakens Pittsburgh at its thinnest position.

Doumit's operation is scheduled for Thursday, when pins will be inserted into his broken scaphoid bone to fuse it.

Doumit, who led NL catchers with a .318 average last season, fractured the wrist bone while batting in Sunday's 11-1 loss to the Atlanta Braves. He initially stayed in the game and did not believe the injury was serious, but he began experiencing pain later that night.

Doumit had an MRI exam on Monday and a CT scan on Tuesday that revealed the fracture. He will be re-examined in about a month to determine when he can start rehabilitation, which cannot begin until the bone starts to heal.

"This is something I didn't see coming," Doumit said. "You do everything you can in the offseason to prepare. ... To have something like this, it's devastating. No one wants to be told they can't play for eight to 10 weeks."

The injury happened less than a week after Pirates manager John Russell said he hoped Doumit would catch 140 games this season. The Pirates are left with two rookie catchers: Jason Jaramillo and Robinzon Diaz, who have a combined 14 major league at-bats.

The Pirates' improved pitching staff has lowered its ERA from an NL-worst 5.10 last season to 3.06 going into Tuesday's game against the Florida Marlins and had four shutouts in seven games but now must work with two inexperienced catchers.

Jaramillo, 26, was added in an offseason trade with the Philadelphia Phillies for Ronny Paulino, Pittsburgh's starting catcher in 2006 and most of 2007. Paulino lost his starting job with the Pirates partly because of training issues and defensive lapses and now plays for Florida.

Jaramillo has made only two career starts, including one Monday night against Florida, and is 3-for-8 this season.

Diaz, 25, was recalled from Triple-A Indianapolis on Tuesday to replace Doumit on the 25-man roster. Diaz, acquired from the Toronto Blue Jays in a trade for infielder Jose Bautista on Aug. 25, was 3-for-6 in two games for Pittsburgh last season.

Doumit is hitting .244 with two homers and nine RBIs this season. He signed an $11.5 million, three-year contract during the offseason despite having numerous injury problems in the past.

Doumit was out for three weeks last season with a thumb injury and concussion. He also missed all but one game during the final seven weeks of the 2007 season (wrist, ankle) and sat out half of the 2006 season (hamstring).