Rockies right-hander Juan Nicasio is likely out for the season following arthroscopic surgery on his left knee.
Doctors removed ''four significant pieces'' from Nicasio's left knee, Colorado manager Jim Tracy said.
''It was a very good thing we did the surgery,'' Tracy said. ''... He is more than likely done for the season. The timeframe from a rehab standpoint would more than likely end his season.''
Nicasio went on the 15-day disabled list June 2 after twisting to field a ground ball hit by the Dodgers' Elian Herrera the day before. He twice had fluid drained from the knee, most recently Wednesday, before having the surgery.
''Chunks of bone break off and you've got to go in there and get them out of there,'' Tracy said. '' Those chips get into the joint and it fills up with fluid to protect the area.''
Nicasio is 2-3 with a 5.28 ERA in 11 starts this season.
This is the second straight year Nicasio's season was cut short.
Last August, Nicasio was knocked unconscious when he was hit in the head by a line drive by the Nationals shortstop Ian Desmond. Nicasio fractured his C1 vertebrae when he fell to the ground. He had surgery and missed the rest of the season.
He made a quicker than expected recovery and was on the opening day roster, where he was a frontline starter for Colorado before hurting his knee.
The Rockies' rotation has been plagued by injuries. Projected ace Jorge De La Rosa has been out since tearing a ligament in his pitching elbow in May 2011. The lefthander had Tommy John surgery and was expected back before the All-Star break this season but has had several setbacks in his rehab.
Righty Jhoulys Chacin hasn't pitched since May 1 because of a nerve issue in the right side of his chest.