The announcement will come at 10 a.m. ET from the Yankees' spring training camp in Tampa, Fla. Rivera, who is coming off surgery to repair a torn ACL in his right knee, then will pitch against the Atlanta Braves. It will be Rivera's first appearance this spring.

The New York Post initially reported Rivera's decision.

Considered the greatest closer in baseball history, Rivera, 43, will retire as the all-time saves leader. He enters the 2013 season with 608 saves, seven more than Trevor Hoffman's career total.

Rivera's 42 postseason saves are nine more than the combined total of the next two on the list, Brad Lidge and Dennis Eckersley. Rivera has won five World Series rings with the Yankees, his only big league employer.

Rivera returned home this week for a personal matter, and was expected to rejoin the team Saturday.

"He is the greatest closer of all time," Girardi said. "There is no question in my mind. I have had the thrill of catching him. I was really there when he burst on to the scene and he was a dominant setup man, and then to see what he did as a closer was a thrill for me. I know there is a press conference on Saturday, and we'll go from there."

Hank Steinbrenner declined to say what would be announced at Saturday's news conference. But the Yankees co-chairman said he would like Rivera to remain involved with the team when he does end his playing career.

"If he wants to, that would be my preference," Steinbrenner said. "I think he'd be a great influence, even if it's only at spring training."

The thinking all spring has been that this season would be Rivera's last. Rivera has always said he wanted to tell the people most important to him before making any announcements about his future.

There had been a feeling that Rivera would call it a career after 2012: In spring training last year, he had hinted that it might be his final season. After getting hurt, though, he vowed to return. He injured his knee while shagging balls in the outfield before a game in Kansas City last May.