NEW YORK -- Here’s the funny thing about Luisangel Acuña’s hot streak over his first few days in the Majors: If he keeps it up, he may just knock his brother’s team out of the playoff race.

In just his fourth Major League game on Tuesday night, Acuña collected his first career extra-base hit, his first RBI and then the loudest blow: his first home run, a shot to left-center field to provide the final run in a 10-1 rout of the Nationals at Citi Field.

Acuña is now 5-for-11 since his callup on Saturday.

“He’s just calm, poised,” manager Carlos Mendoza said. “It’s just like he belongs in the big leagues.”

“I think this is something that I earned,” Acuña replied through an interpreter when told of Mendoza’s comments, “and what he says isn’t a lie.”

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Even though Tuesday’s game began inauspiciously for him, with a third-inning fielding error that gift-wrapped the Nationals their only run, Acuña found a way to overcome that start. In the bottom of that inning, he doubled to center field to tie the game, then scored from third on a Pete Alonso single. In the sixth, Acuña singled and scored again, before launching his first career homer in the eighth.

That ratcheted up the energy at Citi Field, where fans exploded again about five minutes later when the Braves -- the employer of Acuña’s older brother, Ronald, who is out for the season -- lost to open up a two-game National League Wild Card lead for the Mets.

“Hopefully, we can continue to have that energy of the fans here at Citi Field,” Acuña said. “I’ve never played in front of so many fans and especially so many passionate fans.”

More and more, Acuña is ensuring that if the Mets do play October baseball in Queens, he’ll be a part of it.

Right now, Acuña is here largely because Francisco Lindor remains sidelined with a lower-back injury. The Mets had been considering a callup of their No. 12 prospect for some time, and Lindor’s injury pushed them over the edge last weekend.

But with Jeff McNeil injured and backup infielder Eddy Alvarez ineligible for the playoff roster because he was acquired after Sept. 1, Acuña could eventually become the primary backup to Lindor and Jose Iglesias. He’s the only other healthy middle infielder on the 40-man roster. And Acuña is versatile, too, capable of playing second base, shortstop and center field.

Currently, those decisions are not on the radar screens of team officials, who are more concerned about making the playoffs than about what their roster might look like in October. But if Acuña keeps hitting with Lindor sidelined, such conversations will eventually happen.

“He had a hell of a night, and I hope he has many, many nights like that in his career,” Alonso said. “It’s a super-exciting start for him.”