SURPRISE, Ariz. -- Royals pitcher Julio Pimentel didn't know what to think. He threw a pitch, heard something pop and, puzzled, looked around.

"I was throwing and, gosh, I heard this noise," Pimentel said. "I looked at my feet, I thought I hit a rock."

Then his right hand started shaking and his elbow began swelling. That's when he knew something was really wrong.

That was last Friday when he threw a fastball, a good one for a strike, to the Rangers' Hank Blalock. And that was the last pitch that Pimentel, a promising rookie, will be throwing for a while.

The Royals on Monday reported that an MRI revealed a bone spur fracture in his right elbow. It's a non-displaced fracture adjacent to the ulnar collateral ligament and there are two options: 1. Let it heal on its own, or 2. have corrective surgery.

Pimentel will see a doctor for a second opinion on those options this week. Even without surgery he's expected to miss at least six weeks.

He's on the Royals' 40-man roster and was acquired on July 25, 2006, from the Los Angeles Dodgers along with pitchers Odalis Perez and Blake Johnson in exchange for pitcher Elmer Dessens.

Pimentel had a big season in 2007 for Class A Wilmington with a 12-4 record and 2.65 ERA. Last year, he made 28 starts for Double-A Northwest Arkansas and finished 7-13 with a 5.38 ERA. He was fourth in the Texas League in strikeouts (115) and innings pitched (157 1/3).

He represented the Royals in last year's Futures Game at Yankee Stadium and pitched a scoreless inning for the World team in a 3-0 victory over the U.S. He's from La Romana in the Dominican Republic.