PITTSBURGH — Another new Yankee is dealing with a back issue. 

Cody Bellinger was out of the Yankees lineup Friday against the Pirates because of a stiff back that popped up during Thursday’s game. 

“Not something I want to mess with,” manager Aaron Boone said Friday afternoon before a 9-4 win at PNC Park. “I don’t think it’s anything too big.” 

The outfielder’s condition improved slightly after Thursday’s victory against the Diamondbacks, as confirmed by Boone. However, following a late flight and arrival at the team hotel at approximately 2:30 a.m. on Friday, the Yankees opted to err on the side of caution.

Bellinger also reported feeling “a little” better Friday morning, and Boone expected him to be available off the bench, though the Yankees did not need him. 

“I just felt like, ‘Let’s give it a day to try to calm it down,’ ” Boone said. 

Paul Goldschmidt, who joined Bellinger as the main addition to the Yankees’ lineup this season, also dealt with a back issue late in camp but took a few days off, and it has not been an issue since. 

With Bellinger out of the lineup, Trent Grisham was back in center field for a second straight game. 

In an all-too-familiar development, Scott Effross is hurt again. 

The reliever had a setback while rehabbing his hamstring strain, putting him in a holding pattern instead of advancing to face hitters and getting closer to being an option for the Yankees. 

Effross initially hurt his hamstring on his first pitch of a Feb. 25 Grapefruit League game.

He had entered camp feeling good after a long road back from Tommy John and back surgeries but now is back in the trainer’s room. 

Adam Ottavino’s reunion with the Yankees was a short one, as the Yankees designated the veteran reliever for assignment Friday to make room for Devin Williams returning from the paternity list. 

Ottavino had signed with the Yankees on Tuesday (when Williams landed on the paternity list) and made two scoreless appearances spanning 1 ¹/₃ innings in their series against the Diamondbacks.

He walked two and struck out two. 

The 39-year-old now heads back into limbo, where he had been before Tuesday after spending spring training on a minor league deal with the Red Sox and not making the team. 

Williams, meanwhile, pitched the ninth inning Friday, his first appearance since Opening Day. 

The Yankees signed utilityman Cooper Hummel to a minor league deal Friday.

The 30-year-old switch-hitter, who plays catcher, left field and first base, has hit .159 with a .531 OPS across 82 major league games.

He has been better in 330 games at Triple-A, batting .285 with a .900 OPS. 

Tyler Matzek (oblique strain) has been facing hitters in Tampa and his next outing could be the start of a rehab assignment with Single-A Tampa.

The lefty reliever is expected to be ready before the end of the month.

Luis Gil (lat strain) is about a week or 10 days away from potentially starting to play catch, Boone said, which would mark the end of a six-week shutdown.

Jake Cousins (forearm strain) is less than a week away from getting on a mound, Boone said.