Kansas City Royals third baseman Mike Moustakas has had season-ending surgery on his right knee.

Moustakas tore his anterior cruciate ligament in a May 22 collision with teammate Alex Gordon. The team says Thursday that the operation was performed by Dr. James Andrews in Pensacola, Florida.

Moustakas was a key player in helping Kansas City win the World Series last season and was selected to the AL All-Star team. He batted .240 with seven home runs in 27 games this year.

Gordon broke his wrist in the collision and the left fielder also is on the disabled list.