New York Yankees closer Mariano Rivera suffered a torn anterior cruciate ligament in his right knee, an injury that could potentially end his illustrious career.

He tore the ACL during batting practice Thursday prior to his club's game against the Kansas City Royals.

Rivera, 42, injured his knee while attempting to snag a fly ball along the warning track. He leapt at the wall and as he came down, his knee buckled underneath him. He immediately clutched at his knee and was in visible pain.

"I grabbed myself between the grass and the dirt. I couldn't pull my leg up and twisted it (the knee). It's an ACL. Torn actually. Meniscus also," Rivera said.

Rivera, whose 608 saves are the most in MLB history, had to be carted off the field as concerned teammates and coaches looked on.

"I don't know" was his response when asked if he'd be able to pitch again.

"It all depends how the rehab is going to happen," Rivera said. "From there, we'll see."

He initially thought the injury wasn't that severe.

"I thought it wasn't that bad," Rivera said. "I mean I was walking a little bit. But it's torn. I have to fix it."

Rivera regularly shags fly balls during batting practice as a way to keep in shape.

He has five saves and is 1-1 with a 2.16 earned run average in nine games for New York this season.