Mariano Rivera, the greatest relief pitcher in major league history, intends to retire at the end of the 2013 season. The New York Yankees' closer is supposed to make the announcement official at a press conference at Steinbrenner Field in Tampa on Saturday morning.

Rivera was scheduled to retire at the end of the 2012 season, but he postponed retirement after he suffered a torn ACL in his right knee last May while shagging fly balls before a game in Kansas City. In 18 years with the Yankees, Rivera has compiled a major league record 608 saves and 892 games finished. He was a key member of five World Series-winning teams.