NEW YORK Yankees manager Joe Girardi said closer Mariano Rivera has a torn right knee ligament, an injury that could potentially end his career.

The 42-year-old righthander was carted off the field after twisting his right knee shagging fly balls during batting practice Thursday night before the Yankees' 4-3 loss to the host Kansas City Royals, who were led by Mike Moustakas' three RBI.

Girardi revealed the severity of the injury after the game. Royals team doctor Vincent Key diagnosed a torn ACL after looking at the MRI.

"This is bad, there's no question about it," Girardi. "

Rivera, baseball's career saves leader, was examined by Royals associate physician Dr. Joe Noland and Yankees trainers, and was sent immediately for an MRI exam at KU MedWest.

Rivera, who has spent his entire 18-year career with the Yankees, was tracking down a ball hit by Jayson Nix in deep centerfield when his right knee appeared to buckle a step before the wall. He fell to the warning track and immediately grabbed at his right knee, briefly covering his face with his glove and grimacing in pain.

Near home plate, teammate Alex Rodriguez could be seen saying, "Oh, my God. Oh, my God."

Rivera (1-1) blew the save on Opening Day, but he's only allowed two hits in eight scoreless innings since then, picking up five of his 608 career saves.

In other news, Yankees third baseman Eric Chavez was released from the hospital and put on the 7-day concussion disabled list. He hurt himself when he dove for a ball in a game against Baltimore on Wednesday.

In other games * 

At Chicago, Jason Kipnis hit a three-run homer and finished with a career-high four RBI, leading the Cleveland Indians to a 7-5 victory over the White Sox.

* At St. Petersburg, Fla., Jeff Keppinger hit a two-run homer and Desmond Jennings added a two-run triple to help the Tampa Bay Rays beat the Seattle Mariners, 4-3, to complete a four-game sweep.

* At Anaheim, Calif., Brandon Morrow (3-1) struck out eight over nine innings and J.P. Arencibia hit a three-run homer to lead the Toronto Blue Jays to a 5-0 win over the Los Angeles Angels.