BRADENTON, Fla. -- New York Yankees catcher Gary Sanchez was scratched from batting practice Saturday due to a sore back, although manager Aaron Boone said he doesn't think the problem is serious.

Boone said he thought the soreness stemmed from Sanchez playing back-to-back games for the first time in spring training. Boone said he expected Sanchez would be shut down on Sunday, but didn't rule out a return to game action in a few days.

"His back was a little sore this morning," Boone said. "Nothing I'm too concerned about. I think that's kind of normal wear and tear [after] first back-to-backs kind of thing. I don't think it will be much of an issue."

Sanchez joins a growing list of Yankees' regulars impacted by injuries.

The team announced Friday that slugger Aaron Judge has a broken rib. It's not clear whether he will need surgery, leaving doubt as to when he'll be back in the lineup.

Judge will rest two weeks while recovering from the stress fracture to his first right rib. He hasn't played in any spring training games while dealing with soreness in his right pectoral muscle and shoulder.

Two other Yankees outfielders also are out. Giancarlo Stanton strained his right calf on Feb. 26 during defensive drills and will miss opening day on March 26. Center fielder Aaron Hicks had Tommy John surgery on his right elbow on Oct. 31 and is not expected back until summer.

Boone said Stanton played catch, and hit off a tee and took soft toss Saturday in an indoor cage.

New York will also start the season without three of its top five starting pitchers: Right-hander Luis Severino will miss the season following Tommy John surgery on Feb. 27; left-hander James Paxton is likely out until late May or June after surgery to repair a herniated disk in his back and to remove a cyst; right-hander Domingo German must serve the final 63 games of an 81-game suspension for violating Major League Baseball's domestic violence policy.

Severino said Saturday that he's feeling pretty good but frustrated about getting hurt for the second straight year.

Severino said one of the first things he did after finding out that he needed Tommy John surgery was to check the internet to find pitchers that have had success after the procedure.

Two names that immediately popped up were two-time NL Cy Young Award winner Jacob deGrom and 2019 World Series MVP Stephen Strasburg.

"A lot of good pitchers came back from that. so I think that gives me more confidence," Severino said. "These guys did it; I can do it, too. It's going to be a long recovery, but at least I'm sure that I'll be good for next year."

The Yankees had Severino go to New York twice over the winter for MRIs and a CT scan looking for the cause of occasional discomfort, but the tests were all negative.

The discovery of a partial UCL tear last month at least provided some answers.

"Definitely," Severino said. "In your mind you're thinking about a 100 things that can happen. Now, it's good to know what I have. It's good to know one part; it's not good to know the other part."