Mariano Rivera tore the ACL and meniscus in his right knee Thursday night catching fly balls in the outfield during batting practice.
Rivera was running back on a ball hit to center field when his knee buckled near the warning track and he crumpled to the ground. He was holding his right knee and witnesses report him being in "severe pain."
"It appears he has a torn ACL," manager Joe Girardi told reporters after the Yankees dropped a 4-3 game to the Royals. "If that's what it is, it's pretty much as bad as it gets."
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The Yankees will send Rivera back to New York to be examined by their own doctors, but at this point it's all but a given. He would be out for the season.
"You have to take it the way it is and just fight through it," Rivera said after the game.
"It's not what you want, but it's not season over," Girardi said. "You have to find a way to overcome it."
"It's bad. It's bad," Derek Jeter said. "There's no other way you can put it. ... There's no other guy like him."
MLB has posted video from YES of the accident.
The all-time saves leader was carted off the field and then helped into the locker room by Girardi and trainer Mark Littlefield. He wasn't putting any weight on his right leg.
Rivera regularly shags balls before every game and Girardi said he's never had a problem with it, saying he's never been "reckless" in doing so.
Girardi said he would take a night to think about who would replace Rivera, but David Robertson or Rafael Soriano appear to be the obvious candidates. Rivera hasn't bee on the DL since March 2003, when he injured his groin. He didn't pitch for the first month of the season, but returned April 30. Robertson was 17 years old and still in high school in Birmingham, Ala.
Rivera had said before the season that he had made up his mind about whether he would , but wouldn't tell anyone else. If he were to rehab the injury and not retire, he could be ready for the start of the 2013 season. He was non-committal after the game as to his future.
"At this point, I don't know [if I'll pitch again]. I have to face this first," Rivera said. "Whatever happens is going to happen. From there, we'll see."
Follow Metro New York Sports Editor Mark Osborne on Twitter @MetroNYSports.