"I didn't feel anything was bothering me, just the last couple hitters," Diaz said.
• Rockies Spring Training info
The results were expected Monday, but the Rockies released the information about the injury and pending surgery Sunday evening.
Manager Walt Weiss said he noticed Diaz "didn't look right," and removed him in short order. Diaz, who turns 25 in May, went 0-1 with a 2.37 ERA in 21 appearances late last season, after spending much of the year at Triple-A Albuquerque.
Diaz not only was a candidate for the Opening Day bullpen, but his velocity made him a possibility for late innings. Acquired from the Angels for infielder Josh Rutledge before last season, he has been pegged as possible closer material.
The Rockies possess a cadre of young righties vying for jobs. Miguel Castro, Simon Castro, Justin Miller, Scott Oberg saw Major League action last season. Carlos Estevez, coming off a big strikeout season at the Class A and Double-A levels, has impressed early in camp. They're also taking a look at Matt Carsiti, a sixth-round pick in 2012 who turned heads at Class A.
Lefty Sam Moll, who has handled right- and left-handed hitters effectively, has worked into the mix. Also starter Chris Rusin, swingman Yohan Flande and starter Tyler Matzek, who could be a candidate if he curbs his wildness, are on the radar.
• Left-handed starter candidate Chris Rusin, nixed from a start Friday because of left middle finger inflammation, felt better Sunday and should resume throwing.
• Righty David Hale did some running after Saturday's 25-pitch bullpen session. Hale will have to practice fielding and covering first base before being cleared for Cactus League games, Weiss said.
• Outfielder Gerardo Parra was removed from Saturday's game with right ankle/heel soreness, but he reported feeling fine Sunday and Weiss said he removed Parra only for precautionary reasons.