FORT MYERS, Fla. — In a perfect world, Will Warren would have shown the Yankees what he was made of without failing to make it out of the first inning Sunday.

But that was the position in which Warren found himself, and the young right-hander still made a strong impression anyway as he continued to make his case to fill Gerrit Cole’s spot in the rotation to begin the season.

In what was likely his penultimate start of the spring, Warren got knocked on his back in the first inning against the Red Sox at JetBlue Park.

He faced seven hitters and recorded only one out, and while his defense was no help with a pair of fielding errors, he also gave up some loud contact.

Will Warren (98) throws a pitch against the Boston Red Sox in the first inning at JetBlue Park at Fenway South.

Aaron Boone pulled Warren with his pitch count rising and the Red Sox leading 5-0, but spring training rules allowed him to return for the second inning, when the 24-year-old got back to work.

Seemingly unfazed by the rough first inning, Warren responded by retiring eight of the next 10 batters he faced to make the best of the situation.

“Certainly a struggle [in the first inning], but kind of showed us who he was,” Boone said. “I thought he was pretty sharp the rest of the way. Unfettered. In fact it’s times like this you learn a little more, even more about a guy. I think he’s really good. I think he’s really good right now.”

Knowing what was on the line in this start — his first since the Yankees got the diagnosis on Cole’s elbow issue that will sideline him at least until the end of May — Warren could have gotten flustered by the Red Sox ambushing him in the first inning or the two errors behind him.

Instead, he exuded the quiet confidence the Yankees have liked about him and found a way to settle into his outing, striking out five while building his pitch count up to 68.

“I think that goes into the factor of proving that you belong there,” said Warren, whose costliest mistake was a hanging slider that Trevor Story crushed for a three-run homer. “When you get hit in the mouth, how do you bounce back? How do you respond to how bad the first inning was, in my opinion, to how the next couple look? At the end of the day, you gotta keep your team in the game. That’s what that next second, third inning portrayed.”

Since the start of camp, multiple people around the team have indicated a belief that Warren was ready to pitch in the big leagues.

That notion has not lost any steam throughout the spring, only taking on more significance now that the Yankees actually have a rotation spot up for grabs.

Luis Gil, Cody Poteet, Luke Weaver and Clayton Beeter (who pitched behind Warren on Sunday, giving up three runs across four innings) are also in contention to fill the fifth starter job.

But the way Boone talked about Warren before and after Sunday’s game was reminiscent of how he often sounded talking about Anthony Volpe around this time last year when the shortstop was trying to make the team.

Will Warren pitches in the third inning against the Rays on Feb. 27 in spring training game.

“I’m overstating it, but I sometimes feel like when I meet a young player that’s maybe not there yet — and it can look a lot of different ways — it’s like, ‘That guy’s a big-leaguer,’ without even watching him,” Boone said before the game. “I kind of have that feeling about Will. … Then now seeing how he goes about things, he’s got an edge, a competitive edge to him.”

GM Brian Cashman on Saturday had cited Warren not being overwhelmed or intimidated by anything, and handling things well in situations where his heart rate might increase.

Sunday offered another example of that in how Warren responded to things going haywire in the first inning in his first taste of pitching against the Red Sox, albeit in a Grapefruit League game.

“I told him, I feel like that’ll be one of those that you always remember your first Red Sox game,” Boone said. “I think he’s going to be really good. I think he’s going to have a career in this game. That’ll be one of those he can share with people: ‘Yeah I went down and took my lumps down at JetBlue [Park] in spring.’ I liked how he responded from it. In the end, he got a lot of good work in and we build from here.”