Will Warren 

 Will Warren  Credit: Newsday/J. Conrad Williams Jr.

FORT MYERS, Fla. — A rival American League scout, speaking Sunday morning about some of the Yankees’ top prospects, quickly got to righthander Will Warren.

What stands out the most about Warren? “His competitiveness,” said the scout, a former big-leaguer who has seen Warren throughout his development in the minors. “Nothing fazes him. Doesn’t get rattled, even when things are going to hell.”

That attribute received quite the test Sunday, and Warren passed.

The 24-year-old, in contention for the fifth starter job, had his worst outing of spring training against the Red Sox.

Leadoff man Jarren Duran reached on an error by shortstop Kevin Smith, the start of a nightmare first inning in which the Red Sox sent 14 to the plate and scored nine runs in the Yankees’ 12-6 loss at jetBlue Park.

But don’t look at Warren’s final line: six runs (two earned), six hits, zero walks and five strikeouts in 2  2⁄3 innings.

The Yankees weren’t.

In fact, reading between the lines, it’s not a stretch to say that Warren, who threw two scoreless innings after the first, has emerged as the favorite to open the season as starter No. 5 (those internal discussions, very much underway, will heat up this week).

“Certainly a struggle, but kind of showed us who he was,” Aaron Boone said. “I thought he was pretty sharp the rest of the way. It’s times like this where you learn even more about a guy. I think he’s really good. I think he’s really good right now.”

Warren, pulled after seven hitters — six of whom reached base, including another on an error — in the first, returned in the second, which MLB’s spring training substitution rule for pitchers allows, and struck out two of three batters.

He allowed a single in the third but struck out two more batters.

“He handled it beautifully,” another rival AL scout said of Warren’s first inning. “The two errors didn’t impact him one bit. Hung some breaking pitches. He will be fine.”

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

Warren, though not thrilled with the hard contact he allowed in the first, focused on his response.

“You’re going to get hit in the mouth sometimes,” he said. “It’s all about how you come back from it . . . How can you get outs as quick as possible using the stuff you’ve got that day?”

Clayton Beeter, also in the competition and mostly sharp during spring training, was not Sunday. He allowed three runs, five hits and a walk in four innings, striking out two.

Luke Weaver, Cody Poteet and Luis Gil are in the mix as well, with the latter now getting strong organizational consideration for a role of some kind out of camp because of the electricity of his stuff during his last two outings.

n  Extra bases

DJ LeMahieu immediately dropped to the dirt during Saturday’s game after fouling a ball off the outside of his right foot. Boone said before Sunday’s game that he was sent for X-rays, which came back negative. “He was pretty sore,” Boone said of LeMahieu’s condition Sunday morning. LeMahieu, troubled by another injury to his right foot a couple of years ago — this one to his big toe and second toe — received treatment on the foot Sunday at Steinbrenner Field. He did not go through a workout, but observers said he seemed to be walking OK . . . Aaron Judge, who has not played since coming out of a March 10 game after two at-bats because of an abdominal issue, hit indoors for a third straight day, this time off a velocity machine . . . Tommy Kahnle (shoulder), who will start the season on the injured list, threw a 20-pitch live batting-practice session Sunday. He has said he’ll need at least three live BPs before getting into a game.

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