"Joba Chamberlain went on the disabled list yesterday and nobody knows when the right-handed bridge to Mariano Rivera will return.

The Yankees are so concerned they are sending Chamberlain for a second MRI exam today after yesterday's MRI exam revealed a strained flexor tendon. Today's MRI exam will include a dye contrast, which is more thorough.

"That [problem] can lead to a long time," general manager Brian Cashman said after last the Yankees' 11-6 loss to the Red Sox last night at the Stadium. "We have had guys in the past that it took a month."

The biggest fear is that often flexor tendon problems are the precursor of elbow ligament damage, which requires Tommy John surgery.

"[Today] we will have a better feel for what we are dealing with," Cashman said.

Chamberlain, who has pitched very well since Rafael Soriano went on the disabled list on May 17 with elbow inflammation, and the Yankees can't pinpoint when the problem surfaced.

"He will be off 10 to 14 days and hopefully start a throwing program," manager Joe Girardi said.

According to Girardi, Chamberlain has been working with a tender arm for the last couple of weeks. but the manager didn't believe Sunday's 35-pitch outing, Chamberlain's season high, in Anaheim was the reason for the injury.

"We have been careful with him with what we have done," Girardi said of Chamberlain, who hadn't allowed a run in his last eight appearances and had given up seven hits and fanned seven in 9 2/3 innings. "He played catch [Tuesday] and the arm felt pretty good [Wednesday] but we had the doctor look at it and they did an MRI. It's pretty amazing, he probably pitched with it for a while.""