Joe Girardi had no second thoughts about putting relief pitcher Bryan Mitchell at first base on Sunday — even though Mitchell hadn’t played there since high school.

Girardi unwittingly chased an obscure bit of history when he sent Mitchell to first base in the 10th inning of what would turn into a 7-4, 11-inning loss to the Orioles. Not since 1989 had a major-leaguer pitched, played first, then pitched again in the same game. That was the Brewers’ Chuck Crim.

Girardi didn’t know if Mitchell had ever played the position before. “I don’t think so. I didn’t ask,’’ he said after the game.

After Mitchell pitched a scoreless ninth and the Yankees tied it at 4-4 in the bottom of the inning on Didi Gregorius’ two-out, two-run single, Girardi wanted closer Aroldis Chapman to work the 10th, and not one inning more. Because the bullpen was depleted, Mitchell played first base, and when the game entered the 11th, he went back to the mound. He gave up three runs and took the loss.

Did the layoff hurt Mitchell?

“He got two outs and he had a runner on,’’ Girardi said. “He saw three hitters before he gave up the run-scoring single, and it was a ground ball. It’s a little unorthodox. Sometimes you sit through long innings in a sense and you’ll go down below and throw like he did today. But just trying to win the game.’’

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Girardi did have some concerns about using Mitchell at an unfamiliar position and, sure enough, he went 1-for-2 in the field, missing one pop-up and catching one. Both were in foul territory and no damage was done on the scoreboard. Mitchell was able to laugh that part off, and when he caught the second one, the crowd responded by chanting his name.

“You worry about can they handle the job,’’ Girardi said. “The thought process that goes into it is I have a strikeout pitcher [Chapman] on the mound, you don’t assume there’s going to be too many ground balls over there. It’s a unique portion of the game where you’re short on pitchers, I got a strikeout pitcher on the mound that I feel good about, and this way the chances of him handling a ball are probably not too good. Now, if you have a ground-ball pitcher and they have a bunch of lefthanded hitters coming up, it’s probably a different story.’’

What did Girardi think when the two pop-ups were hit toward Mitchell?

“You’re like, ‘Oh, my goodness,’ ” Girardi said. “And then he started running after every pop-up when he was on the pitcher’s mound. We were trying to figure that out.’’

Mitchell wasn’t around Monday to explain that. With the Yankees needing a fresh reliever who could pitch extended innings if necessary, he was optioned to Triple-A Scranton/Wilkes-Barre and righthander Luis Cessa was recalled.

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With Erik Boland