NEW YORK -- Working into a position of prominence in the Yankees' bullpen has apparently come at a cost for David Robertson. The team announced Tuesday that it has shut Robertson down indefinitely with tightness in his right elbow and will send him to specialist Dr. James Andrews in Birmingham, Ala., for evaluation.

"It's a concern of mine because he's been a huge part of the bullpen," manager Joe Girardi said. "He gets strikeouts. He's important in tight ballgames coming in with runners in scoring position. Strikeouts are important, and he's been as good as anyone in baseball in getting that. So it is a concern of mine. Hopefully, when we see Andrews, we will get some good news."

After first experiencing discomfort -- not pain -- two weeks ago, Robertson continued to pitch, compiling five strikeouts over three shutout innings in September. But the discomfort has increased to the point that the Yankees have grown concerned.

The club administered an MRI on Monday and will ask Andrews to review the results. No date has been set for the appointment.

"I don't feel like there's anything really seriously wrong," Robertson said.

Yet just the fact that Robertson is making the trip to Alabama is disconcerting for the Yankees. Known as the league's foremost practitioner of Tommy John elbow ligament replacement surgery, Andrews has delivered bad news for countless Major Leaguers in recent years.

Because he does not feel any sort of pain, Robertson said he was not overly concerned. But he has been feeling tightness for roughly two weeks in what has been a breakout season.

In 41 innings, Robertson has struck out 61 batters and posted a 3.29 ERA, working as a middle reliever in the Yankees' bullpen.

"The interesting thing is it's unusual how well he's pitched," Girardi said. "He's looked great."

Mostly, Robertson said, he has been feeling tightness the day after he throws. But lately, that sensation has lingered even when he has gone multiple days at a time without pitching.

Even so, without a diagnosis, Robertson said that he will not stress.

"I feel confident that this is not going to be anything," Robertson said. "I feel like I'm going to be able to come back."