New York Yankees pitcher Phil Hughes has upper back stiffness and will be sidelined for a few days.

"There's always a little bit of concern, but it's upper back by his shoulder blades, so we'll see how he is in a couple days," manager Joe Girardi said Tuesday from the team's spring training site in Tampa, Fla. "You're usually more concerned about the lower [back problem] lingering. The good thing is he was ahead of where he'd probably normally be at this time, which helps."

Hughes was hurt Monday during a defensive drill covering first base.

Closer Mariano Rivera did throw, 36 pitches during his third bullpen session, and is ready to face batters for the first time since May.

"I think the next one's going to be BP," Rivera said.

Baseball's career saves leader was hurt while shagging fly balls during batting practice in Kansas City on May and had surgery June 12 to repair a torn anterior cruciate ligament in his right knee.

A small group of fans watched the 43-year-old right-hander throw and gave him a loud cheer afterward. One fan asked how he felt, and Rivera replied "fine, and how are you?"

Rivera usually pitches seven or eight innings in spring training games.

CC Sabathia threw 30 pitches in his second mound session and said his control was better. The left-hander had arthroscopic surgery Oct. 25 to remove a bone spur from his left elbow.

Rivera and Sabathia are both expected to be ready for opening day.

Right-hander David Phelps, who threw 30 pitches during two innings in a simulated game, is scheduled to start Saturday's spring training opener against Atlanta. Adam Warren is expected to start Sunday's home exhibition opener with Toronto.