TAMPA — Mariano Rivera threw 21 pitches off a bullpen mound for the first time this spring.

“At his age, I have an idea what I need,’’ the 40-year-old closer said. “In my case I don’t have to come in and impress anybody. For the first bullpen it felt real good.’’

Rivera is likely to throw at last three more ‘pens before attempting batting practice. Don’t look for him in a game before March 16.

“He is a lot further along than he was at this time last year,’’ Joe Girardi said of Rivera, who was coming back from shoulder surgery a year ago. “The ball looked good coming out of his hand.’’

According to Girardi, Rivera needed “six weeks to two months’’ last year before he was fully recovered from the surgery.

As for the shortened spring workload, Girardi said, “He gets plenty of work during the season. We keep it to a minimum down here.’’