Aaron Hicks said he “flat-out” missed it.

The outfielder, brought in this offseason because of his ability to hit lefthanders and, hence, getting the nod in left Tuesday against Astros lefty Dallas Keuchel instead of Brett Gardner, saw Jose Altuve’s liner off the bat in the fourth inning.

But Hicks hesitated a moment, and the ball sailed over his head for a leadoff double. Altuve scored later in the inning, on Carlos Correa’s groundout, to cut Houston’s deficit to 2-1. It was a crucial mistake in a 5-3 loss.

Leftfield at the Stadium is notoriously difficult on sunny days like Tuesday but the 26-year-old, acquired from the Twins in the offseason for catcher John Ryan Murphy, did not use that as an alibi.

“I just didn’t play it well,” Hicks said. “At the crack of the bat I thought it was going to be right at me and I got caught flat-footed and just didn’t make the play.”

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Mitchell has surgery

One of the standout arms from the spring for the Yankees will be lost to them for at least four months.

Righthander Bryan Mitchell, who had a 0.57 ERA this spring in easily winning the swing man role, underwent surgery on his left big toe Monday after seeing a foot specialist in North Carolina.

“It will be at least four months before we see him,” Joe Girardi said before Tuesday’s game.

Luis Cessa, acquired in the offseason as rotation depth for Triple-A but who won a bullpen spot with an outstanding spring, is a candidate, as is Ivan Nova, the loser of the fifth starter competition to CC Sabathia.

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McCann Ok

Catcher Brian McCann grounded out to first against Luke Gregerson to end the game, stumbling out of the batter’s box.

“My cleat caught,” McCann said. “I’m all right.”

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Extra bases

The first-pitch temperature was 36 degrees, the coldest in a regular-season game in the Bronx since April 8, 2003 against the Twins when the first-pitch temperature was 35 degrees . . . Hideki Matsui, a Yankee from 2003-09 and the MVP of the 2009 World Series, threw out the ceremonial first pitch, a solid strike to McCann.