Sport News : Knee injury could end closer Rivera's season

"You lose a Hall of Famer ... if that's what it is, that's as bad as it gets," a sombre Girardi told reporters after New York's 4-3 loss.

The Panamanian right-hander, who has registered a record 608 career saves, suffered the injury while running back in deep center field to chase down a ball hit by Jayson Nix.

It could also mean the end of Rivera's illustrious career. The closer said before the season he had made up his mind whether this campaign would be his last but was not going to reveal his decision until after the season.

Rivera's right knee buckled as he approached the warning track going after the fly ball and collapsed to the ground near the fence, clutching his knee in pain.

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

An MRI scan performed at a nearby hospital revealed the torn ligament, Girardi said.

Rivera, who set the league's saves record with 602 against the Minnesota Twins in September, regularly chases fly balls as do many pitchers during batting practice as part of their conditioning.

Yankees captain Derek Jeter, who has teamed up with Rivera to win five World Series titles with New York, said: "He's going to be missed. There's no other way to put it. "You can't rep lace him."

Rivera, who has also posted a record 42 postseason saves, had shown no signs of slowing down, registering a 1-1 record with five saves and a 2.16 earned run average this season.

"There's reasons why it happens," an emotional Rivera told reporters. "You have to take it the way it is and fight through it. Now we just have to fight."