All-star pitcher Brandon Webb of the Arizona Diamondbacks returned to Phoenix on Thursday with soreness in his right elbow.

The Diamondbacks made the announcement prior to Thursday's road doubleheader versus the Chicago Cubs.

An MRI exam performed on Webb's elbow showed no structural damage in his pitching elbow.

Webb, 27, was expected to miss his scheduled start Saturday against the Houston Astros. It's uncertain when he'll be able to return to action or if he'll eventually be placed on the disabled list.

"How much we push back, we'll see whether it's just a couple of days or a skip," Diamondbacks general manager Josh Byrnes said. "Saturday is unlikely."

Byrnes said Webb has experienced recurring soreness in the right elbow since last month's all-star break.

The discomfort reappeared during his last outing, a 15-4 triumph over the Cubs on Monday. He tossed eight innings in the win.

"He's our most irreplaceable player," Byrnes said.

"He should be the Cy Young winner, at least two-thirds of the way through. But at the same time we have him signed through 2010. We're going to make sure it's right before we put him out there."

Webb is in the midst of a breakout campaign for the Diamondbacks. He has a 12-4 record and 2.74 earned-run average this season and earned his first trip to the all-star game.

The right-hander leads the majors with 167 1/3 innings and is tied for the National League lead with 12 victories.
  

With files from the Associated Press