BOSTON — Luis Severino had pitched at Fenway Park only twice before, and he didn’t especially enjoy the experience. Wednesday night likely went a ways toward changing that.

In perhaps his most impressive outing as a Yankee, Severino threw seven shutout innings in a 3-1 victory over the Red Sox on an eerie 50-degree night, when much of the game was played in mist and dense fog.

“My confidence right now is very good,” Severino said, crediting catcher Austin Romine for much of his success in a win that pushed the Yankees to 12-7. “I was making good pitches, I wasn’t thinking about leftfield or the Green Monster.”

This being Fenway, the Red Sox inserted some theater in the ninth, bringing the potential winning run to the plate against Aroldis Chapman. Andrew Benintendi walked and Mookie Betts doubled off the Monster. Pinch hitter Chris Young’s groundout to third made it 3-1 and, with Hanley Ramirez up, Betts advanced to third on a wild pitch.

Ramirez walked to put runners on the corners for Jackie Bradley Jr., still one out. Chapman recovered, striking out Bradley with a slider, then struck out Josh Rutledge on a 97-mph fastball for his fifth save in five chances. Two pitches before, Rutledge yanked a 97-mph fastball foul down the leftfield line, with much of the crowd shrieking as if it would be a game-winning homer.

“I knew it was foul off the bat,” Romine said. “I had the best seat in the house.”

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Said Chapman: “I knew it was a foul ball.”

After the 33-pitch inning, it appeared Chapman grabbed his arm, but the closer said: “I feel fine. Thank God I feel fine.”

Aaron Judge, who turned 25 Wednesday, co-starred with Severino. The 6-7, 280-pound rightfielder laced a two-run homer in the second inning, banana-slicing a pitch from Rick Porcello (1-3) to rightfield. According to Elias, Yogi Berra and Roger Maris were the only other Yankees to homer at Fenway on their birthdays. Maris was the most recent, on Sept. 10, 1966.

In the third, Judge flipped head over heels into the crowd in pursuit of a foul ball. The effort, which resulted in an out after a replay review, caused just as much elation in the dugout as the home run, his team-leading seventh.

“Adrenaline was pumping,” Judge said. “I saw a ball I could get to and trying to do anything I can to catch it.”

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The 23-year-old Severino’s only other start at Fenway came last Aug. 9, a forgettable game in which he allowed five runs and seven hits in 4 1⁄3 innings. This time he was brilliant from the start.

With a fastball that consistently reached 97, 98 mph throughout and his typically effective slider, Severino (2-1, 3.00) allowed three hits. He struck out six and walked two, giving him 33 strikeouts compared to four walks in 27 innings.

Greg Bird, who was in a 5-for-50 skid to start the season, including 1 for his last 22, lasered a single off the wall in left in the sixth to make it 3-0. “I needed it,” Bird said. “We needed it.”

Dellin Betances struck out two in a perfect eighth before Chapman’s shaky ninth.

Porcello wasn’t bad, allowing three runs (two earned) and five hits in 6 2⁄3, but he was outpitched by Severino, who again excelled with his fastball command.

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“I can sit on a corner and he can dot me up at 97, 98,” Romine said. “He went after guys tonight.”