The New York Yankees suffered a major scare on Thursday when closer Mariano Rivera strained his right knee while fielding fly balls during batting practice before their game in Kansas City against the Royals.

Rivera, who holds Major League Baseball's career saves record with 608, suffered the injury while running back in deep center field to chase down a ball hit by Jayson Nix.

The 42-year-old's right knee buckled as he approached the warning track and he collapsed to the ground near the fence, clutching his knee in pain while grimacing.

Rivera was diagnosed with a strained right knee after being examined on site at Kauffman Stadium by Royals associate physician Joseph Noland and several members of the Yankees training staff.

He was then loaded on to the back of a flatbed truck and driven off to have an MRI scan.

Rivera, who set the league's saves record with 602 against the Minnesota Twins in September, regularly chases fly balls in center field during Yankees batting practice.

(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Ian Ransom)