NEW YORK -- Randy Vásquez’s first game on a big league mound proved he could compete at the highest level. His second showed that he could dominate.

The rookie right-hander returned from the Minors to fire 5 2/3 strong innings, supported by homers from Gleyber Torres and Billy McKinney, to earn his first Major League win as the Yankees secured a split of Thursday’s doubleheader with a 3-0 nightcap win over the White Sox.

“The first start, the experience of pitching up here [taught me] that no matter what happens out there, to keep your head up and keep making pitches,” Vásquez said through an interpreter. “Going through that start allowed me to be better tonight.”

Summoned from Triple-A Scranton/Wilkes-Barre as the Bombers’ 27th man for a twin bill necessitated by Wednesday’s postponement due to poor air quality, the 24-year-old Vásquez limited Chicago to two hits. Ron Marinaccio (2 1/3 innings) and Clay Holmes (one inning) polished off the shutout.

“He just looks like he’s having fun out there,” Marinaccio said of Vásquez. “He’s competing; he’s not scared. We saw that in his first outing against the Padres. It was a bunch of his idols on that team, a bunch of big superstars. He didn’t back down, and he came back up here again and did the same thing.”

Rated as the Yankees’ No. 12 prospect by MLB Pipeline, Vásquez made his Major League debut on May 26 against San Diego, an effort blemished only by a Juan Soto homer. This time, Vásquez was spotless, walking one and striking out three in an 86-pitch effort.

“That was awesome,” McKinney said. “He was getting ahead early, throwing strikes with all of his pitches. It was pretty fun to watch, especially just seeing him down in Scranton, how hard he’s worked. I’m a big Randy Vásquez fan, that’s for sure.”

As expected, the Yanks returned Vásquez to Triple-A after the game, but manager Aaron Boone said the hurler made an impression.

“Between him and Jhony [Brito], they’ve shown us enough that we know we can go down there in a spot and they’re capable of coming up here and having success,” Boone said. “Tonight is only going to bolster his confidence and hopefully continue to bolster his development.”

Vásquez’s effort came after the Yankees dropped the opener of Thursday’s twin bill, 6-5. Luis Severino permitted four runs and six hits over five innings, including home runs to Jake Burger, Luis Robert Jr. and Yoán Moncada.

Severino walked two and struck out six, the second consecutive outing in which he was hit hard, having permitted a season-high seven earned runs to the Dodgers on June 2 in Los Angeles. Somewhat surprisingly for a pitch he considers his best weapon, Severino generated just one whiff on 18 swings at his fastball.

“I’m not 100 percent sure what’s going on, but the bottom line is that I need to fix it. It’s unacceptable,” Severino said. “I can’t go out there and give up three homers every time I get the ball. I need to fix it quick.”

As Vásquez cruised in the early frames of Thursday’s second game, retiring 15 consecutive batters through one stretch, the Yanks took good swings against Chicago starter Mike Clevinger.

Immediately following Willie Calhoun’s video-reviewed double to lead off the fourth inning, Torres snapped an 0-for-20 skid by launching a two-run homer, exacting revenge after he’d fouled out with two men on in the ninth inning of the first game.

“I had a big opportunity and didn’t do the job [in Game 1],” Torres said. “I just tried to do something good for the team. I got another opportunity, and I was more focused than normal.”

McKinney added a solo homer in the fifth. A one-time Yankee farmhand who was part of the July 2016 bounty from the Cubs for closer Aroldis Chapman, the 28-year-old had hit nine homers in 40 games in Triple-A. He’s among a group who could see playing time while Aaron Judge mends an injured right toe.

“Just help the team win; that’s the goal, as many games as you can,” McKinney said. “Obviously, Aaron Judge, he’s one of a kind. The goal is to get him healthy as soon as possible and get him back to playing.”