Rivera at Spring Training Debut: 'I Feel Good' TAMPA - Mariano Rivera could not stop smiling. On the first day of workouts for Yankees pitchers and catchers, Rivera completed the most mundane of drills with a boundless joy usually reserved for children. Nine months after tearing a right knee ligament while shagging balls in the outfield in Kansas City, the 43-year-old Rivera played long toss and threw off a mound for about five minutes on a back field at the Yankees' spring training complex Wednesday morning. Then he jogged without a limp through pitchers' fielding drills. He stayed out for additional fielding work after the others in his group - C.C. Sabathia, Andy Pettitte, Hiroki Kuroda and Phil Hughes - headed inside. "I feel good, thank you very much," Rivera said. It was wonderful to be back there again, especially another spring training. I was grateful, and give to the Lord that he gave me an opportunity to be here. I enjoyed it. Rivera said he wore a small brace on his right knee, and will wear one when he pitches this season. He reprised his cat-and-mouse coyness about retirement, saying he knows whether he will play beyond this season but will not reveal it. He promised to do so before the season starts. "I will let you know when it happens," he said. And manager Joe Girardi couldn't resist a wisecrack when asked whether he will forbid Rivera from shagging during batting practice, a routine since his minor-league days. "Only in Kansas City," Girardi said.