In Tampa and Joel Sherman in Jupiter The most emotional close of Mariano Rivera’s career comes tomorrow. Rivera is set to announce at a 10 a.m. press conference at Steinbrenner Field that the 2013 season will be his final one. True to his private nature, Rivera wanted to keep this matter as quiet as possible until the official announcement. In an interview with The Post, Rivera, in fact, said: “If you hear that [retirement] from me, that will be confirmed. It’s only a rumor until I talk.’’ But that the Yanks have called a press conference is no rumor. It is a fact and multiple sources confirmed it is for Rivera to inform the world this year will be the last of his Hall of Fame career. When Rivera suffered a torn right ACL last May shagging flyballs in Kansas City, whatever plans he had of retiring were scrapped. Rivera said he couldn’t leave the game he loves and has dominated with a cut fastball since 1996 on the back of a golf cart. From the outset of spring training, the belief around the Yankees was that this would be the final year of Rivera’s career. Rivera, though, had said he had made a decision and would not make that decision public until a later date. As of yesterday, he still was unwilling to do so.