KANSAS CITY, Mo. -- Get ready for One Mo Time.

"I am coming back," Mariano Rivera said Friday afternoon in the New York Yankees' clubhouse. "Put it down. Write it down in big letters. I'm not going down like this. God willing and given the strength, I'm coming back."

Rivera's announcement was the second surprise he has delivered over the past two days, the first being his stumble and crumble to the turf while shagging flies before Thursday night's Yankees-Royals game, a mishap that resulted in a season-ending knee injury.

But this surprise was of the happier variety, and Rivera, who was emotionally distraught speaking of the injury in the clubhouse on Thursday night, was practically giddy a day later.

Asked, half-seriously, if he planned to come back with the Yankees, Rivera said, "Oh, yeah. Oh, yeah. They will want the old goat."

GOAT, of course, is the acronym for Greatest of All Time, a title Rivera carries among his particular class of ballplayer, the closer.

And Rivera's decision to attempt, at 42, to continue a career that already has accrued just about every accolade that can be bestowed upon a ballplayer, seemed to energize the 18-year veteran.

"Miracles happen, guys," he said. "I'm OK. I'm a positive man. Everything is good. I feel sorry that I let down my teammates but besides that, I'm OK, and the team will be OK, too."

Rivera said he made his decision while lying in bed during a pain-filled, sleepless night.

"I had a lot of time to think last night," he said. "I decided I can't go out like this. I love to play the game. I don't think, to me, going out like this is the right way. ... I don't think like that. With the strength of the Lord, I have to continue."

His decision was bolstered by a conversation Friday morning with Dr. David Altchek, the New York Mets team physician who performed surgery on Rivera's pitching shoulder after the 2008 season.

"Dr. Altchek said I could be back in three, four, five months," Rivera said. "He said, 'You're a fast healer.' I will do my due diligence, my research. I will talk to whoever I have to. Yeah, it hurts me, I'm sorry that I let my teammates down, but at the same time, I'm positive. I'm positive. This is going to pass. This is going to pass."

Rivera suffered the injury when his cleats caught in the dirt of the warning track at Kauffman Stadium while he was attempting to catch a long batting practice fly ball by Jayson Nix, who only had joined the team that afternoon. Rivera stumbled, his knee twisting awkwardly underneath him, and he lay on the turf writhing in obvious pain and clutching at his right knee.

A subsequent MRI revealed both a torn anterior cruciate ligament and a torn meniscus. Rivera will fly to New York on Saturday to be examined by Yankees team physicians, after which reconstructive surgery will be performed, probably sometime next week.

"Everything is gonna be fixed," Rivera said. "Whatever it is, it's gonna be fixed."

Rivera said he hadn't told his wife, Clara, or his teammates, although he was seen engaged in quiet, intense conversation with Derek Jeter before he spoke with the media. One snippet of overheard conversation -- "You know me, man. I'm gonna work hard" -- gave a hint of what was to come.

"I just kinda had a feeling in talking to him last night that it wasn't the way he wanted to go out," Yankees manager Joe Girardi said. "He still has to get through this rehab, and let's see where he's at. But Mo's a guy who wants to do things on his own terms, and wants to determine when he's done. I don't think he's the kind of guy who would ever want to say I was done because of an injury."

Rivera said he would address his teammates before Friday night's game with the Royals.

"I don't know what I'm going to say. It won't be something that I wrote or anything," Rivera said. "It will be spontaneous, just whatever comes out. It will be encouragement that I trust them and believe in them. I know my group of guys down there. They can do the job. And they will do the job."