With a young teammate making his MLB debut on the mound, the Yankees put on a power display to relieve some of the pressure.

Not that Jhony Brito seemed to be feeling any of it, or needed much help anyway.

The 25-year-old right-hander struck out six over five shutout innings for a strong first impression and the Yankees’ bats took care of the rest, slugging three home runs to win the rubber game against the Giants, 6-0 on Sunday afternoon in The Bronx.

The loudest of the Yankees’ long balls was a 485-foot blast from Giancarlo Stanton, a mammoth two-run shot that landed on the deck above the batter’s eye in center field.

The second-longest home run of Stanton’s career (during the Statcast era, dating back to 2015) put the Yankees up 3-0, two batters after Aaron Judge went deep for the 1-0 lead.

It was more than enough offense for Brito, who looked right at home in his first big-league start while filling in for the injured Luis Severino.

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“I always thought about debuting and having a good debut,” Brito said through an interpreter after giving up just two hits and one walk. “It’s something I’ve thought about [a lot]. The reason why is because you have to be confident to do your job. If you start thinking of bad outcomes, that’s usually when things get out of hand. So, very happy.”

Brito’s strong outing was an important one on a day when the Yankees were short in the bullpen after having to cover 5 ²/₃ innings on Saturday.

It was also important in the larger context, with the Yankees starting the season down three members of their rotation — Severino, Carlos Rodon and Frankie Montas — which suddenly thrust Brito into the picture earlier than expected.

And the Yankees may need him for at least a few more starts, especially after Sunday’s performance.

“His willingness to attack the zone [was impressive],” said catcher Kyle Higashioka, who added a home run in the fourth inning. “That’s probably the most important thing for any young pitcher coming up, you have to trust your stuff and attack the zone or else — major league hitters are going to feel you out and see what you have. If you’re not attacking the zone, they’re not going to chase. He did a great job with all of his pitches, attacking early, and then he got some guys to expand late. Overall I was really happy with it. It was fantastic.”

Brito’s changeup was his best friend on the afternoon, using it to record all six of his strikeouts and 11 of his 16 swings and misses.

Higashioka said the pitch was so effective because it looks similar to Brito’s fastball coming out of his hand, thus leaving hitters guessing at the plate.

Building off the 5 ¹/₃ perfect innings he threw in his final start of the spring, a day after Severino’s injury was revealed, Brito looked at ease on the mound.

He had to throw 27 pitches in the first inning but then found his groove, at one point striking out five straight batters.

“It was fun to watch,” Stanton said. “He was big-time for us. It was good to get his first start the way he did.”

Still, After the game, Brito was optioned to Triple-A Scranton/Wilkes-Barre, according to the Yankees’ transaction page. The team does not need a fifth starter again until April 12, so it could use an extra reliever during that time, with Ian Hamilton being a likely candidate for a call-up.

The Yankees gave Brito the lead in the bottom of the third inning, when Judge and Stanton each delivered their second home run of the season against Giants right-hander Ross Stripling.

Then, after Higashioka homered for the 4-0 lead, the Yankees added a pair of insurance runs in the seventh inning.

It was highlighted by Anthony Volpe leading off with a walk and later stealing third base — his third steal in as many games — which set him up to score on Anthony Rizzo’s sacrifice fly.

But it was Stanton’s gargantuan home run that still had everyone talking about it postgame, including many just shaking their heads at another one of his feats.

“ ‘G’ is weird,” Boone said. “Every time he comes in after one of those I just tell him, ‘You’re weird. You’re different.’ ”