Andy Pettitte, Hiroki Kuroda and Phil Hughes joined Mariano Rivera in the first group of pitchers to throw off a bullpen mound yesterday at George M. Steinbrenner Field during the initial workout of spring training.

Staff ace CC Sabathia throws a bullpen session today and Ivan Nova, who is battling David Phelps for the fifth starter’s spot, threw one Tuesday.

Francisco Cervelli caught Hughes and Chris Stewart worked with Kuroda.

* Since he is rehabbing a fractured left ankle, Derek Jeter is allowed to work out with the pitchers and catchers at the big league facility. However, according to Joe Girardi, Jeter will continue to use the nearby minor league complex instead. Monday is the first full-squad workout and Jeter is expected to participate.

Minor league prospect David Adams’ injury-filled career has another chapter. Adams is dealing with a back problem that according to general manager Brian Cashman could put the second baseman two weeks behind.

Adams, who could be in the mix to replace Robinson Cano if the second baseman leaves as a free agent after the season, was slowed at the start of last season by an ankle injury suffered in 2011, the 25-year-old Adams appeared in 86 games for Trenton (Double-A) and batted .306.

* For player safety, the Yankees are using soft baseballs when hitting grounders to pitchers on the mound. It paid off when Rivera took a grounder off his foot during a drill.

“It’s to make sure you don’t get hurt,’’ said guest instructor David Wells, who hit the grounder that caught Rivera.