DUNEDIN, Fla. — A day after Oswald Peraza went for an MRI exam on his troublesome shoulder, the Yankees were left holding their breath as the infielder went for a second round of testing.

Peraza was set to undergo an arthrogram — imaging that uses dye contrast to examine a joint — on Friday as the Yankees tried to determine the source of his shoulder tightness.

Aaron Boone said he expected to learn more Friday night or Saturday morning, but the fact that Peraza needed more tests after the MRI did not seem like an encouraging sign.

“Let’s see what we get here first and if it’s going to cost him time down or whatever,” Boone said before the Yankees fell, 2-1, to the Blue Jays at TD Ballpark. “I guess we’ll cross that bridge [when] we see what we have and continue to evaluate as we go.”

Back in Tampa, Peraza told The Post’s Joel Sherman he was waiting to hear from the doctor when asked if he was concerned.

Peraza entered camp battling for a bench spot, but any kind of injury would put in question his ability to be ready by the March 28 opener.

“I know Opening Day is coming, but again, I want to wait to hear from the doctor to know what I have,” Peraza said.

Peraza, who has a minor league option remaining, was originally scratched from a Feb. 27 game with shoulder tightness.

A few days later, Boone described it as Peraza’s feeling some “pinching” in his shoulder, but the 23-year-old returned to game action Tuesday.

Peraza played back-to-back games but then came in Thursday reporting more discomfort, with the high-level defender telling Boone he “felt like he really couldn’t rip it across the diamond.”

If Peraza is not available to them, the Yankees will need to determine a backup shortstop to carry on their roster.

Utilityman Oswaldo Cabrera can play the position, but the Yankees may need him to bounce around the field if he makes the roster. Non-roster invitee Kevin Smith, who has big league experience, would appear to be the leading candidate to serve as the backup shortstop.

The Yankees could also look to swing a trade or waiver claim later this month for a backup shortstop who isn’t going to make a roster elsewhere.

Marcus Stroman continued his sharp spring Friday, tossing four no-hit innings against his former team. The right-hander struck out two, walked one and recorded five outs via the ground.

“Just still working,” Stroman said. “The priority now is getting everything down mechanics-wise, stuff-wise, body. There’s definitely a priority on health to build these innings and stay healthy throughout spring training and going into the year feeling good.”

Jasson Dominguez continues to progress in his rehab from Tommy John surgery, scheduled to add left-handed swings to his work Monday (two weeks after he started taking right-handed swings). The outfielder is also throwing out to 75 feet.

“He really hasn’t had any hiccups or bumps so far, knock on wood, which has been really good,” Boone said.