James Paxton nearly got out of the fifth inning having allowed just two runs and delivering just about everything the Yankees could have asked for in Game 1 of the ALDS.

But the lefty gave up an RBI single to Jorge Polanco after a nine-pitch at-bat that tied the game and ended Paxton’s outing in a 10-4 win over the Twins on Friday night.

Ultimately, Paxton gave up three runs in 4 ²/₃ innings in his postseason debut, fighting command issues throughout.

“That was a really good at-bat,’’ Paxton said of Polanco’s turn in the fifth. “He fouled off some really good pitches.”

“I felt good about him going through Polanco,” Aaron Boone said of the switch-hitter. “But we’ll keep him on [the right] side, preferably. He had a great night and a great at-bat against him, but I felt like [Paxton] was pretty strong to that point, and we had [Adam Ottavino] obviously, ready for [Nelson] Cruz.”

Paxton had already given up a homer to Cruz in the third, and even though the Yankees blew the game open late, Paxton’s inability to get out of the fifth forced Boone to go to his bullpen on the early side.

“Of course I would have liked go deep into the game and save our bullpen guys, but I know it’s different in the postseason,’’ Paxton said.

Still, he didn’t look like an ace or, as Aaron Judge called him leading up to Friday’s game, “The best left-handed pitcher in the game.”

Facing a team that set an MLB record by hitting 307 homers during the regular season, Paxton also had to deal with the emotions of pitching a playoff game for the first time.

“There was a lot of adrenaline,’’ Paxton said. “It was intense. I just tried to lock in. I couldn’t feel my body.”

He did manage to impress his teammates.

“He settled in,’’ Judge said. “For his first start postseason, Yankee Stadium, that can be a lot, but he handled it.”

It certainly felt like October, with the chill in the air and the drawn out at-bats and pitching changes.

Paxton said is confident he will be calmer when he takes the mound again, whether that’s in Minnesota or back in The Bronx.

“The atmosphere was great,’’ Paxton said. “It was the loudest I’ve ever heard a stadium. I loved it.”

Next time, he just hopes he’s on the mound later into the game.

“I didn’t know how high my adrenaline would be,’’ Paxton said. “I think it will be better when I know more about pitching in this environment, which I do now.’’