PHILADELPHIA — It came in a disappointing loss, but Luisangel Acuna made his long-awaited MLB debut for the Mets on Saturday and impressed at the plate.

The 22-year-old had a pair of hits in a 6-4 defeat to the Phillies at Citizens Bank Park, where he filled in for the injured Francisco Lindor at shortstop.

Acuna was called up from Triple-A Syracuse in part because Lindor was unavailable after tweaking his back in Friday’s win.

Acuna was largely untested defensively, but he hit the ball hard three times — including on a single up the middle to open the fourth and to right in the ninth off closer Carlos Estevez.

“He looks very relaxed,” said Lindor, who missed his first game of the year. “Ever since I met him, that’s who he is.”

Prior to the game, Acuna said he was playing a video game Friday when he received a call from Syracuse manager Dick Scott, informing him of the promotion.

Acuna said he called his mother with the news and broke into tears. He soon received a call from his older brother, Ronald Jr., the Braves star outfielder, congratulating him.

“In whatever way I can help, whether it be baserunning, hitting, defense, I will be there for whatever the team needs,” Acuna said through an interpreter.

The Mets cleared roster space for Acuna by optioning DJ Stewart to Syracuse.

Acuna provides coverage for the Mets at shortstop and second base in addition to center field.

He was passed over by the team earlier this month when rosters expanded, but team brass had been discussing a promotion for him even before Lindor’s sore back, according to Mets president of baseball operations David Stearns.

And Lindor’s situation pushed the Acuna decision to the finish line.

Acuna arrived to the Mets last summer in the trade that sent Max Scherzer to Texas. He was inconsistent in 131 games this season for Syracuse, although he had 40 stolen bases.

His versatility is welcomed following Jeff McNeil’s wrist fracture that will keep him sidelined for the rest of the regular season.

Once Lindor returns — he is under daily evaluation and may play Sunday — Acuna could receive an occasional start at second base to give Jose Iglesias rest.

“He looked fantastic and had good at-bats,’’ Lindor said. “I’m encouraged with what I saw today. There’s no limit for him.”

The Mets traded for Eddy Alvarez last week, but the infielder will be ineligible for the postseason roster as somebody who wasn’t in the organization before Sept. 1. Acuna would be eligible for a postseason roster spot, but Stearns downplayed the notion of these final two weeks of the regular season serving as Acuna’s acclimation period for October.

“Postseason rosters are a long way away,” Stearns said. “We’ll tackle that when we get there.”

The Mets, who began the day one game ahead of the Braves for the National League’s third wild card, will play three potentially big games at Atlanta in the final week of the regular season. Acuna said he is looking forward to the matchup against his brother’s team, even with Ronald finished for the season after tearing the ACL in his left knee in May.

“It’s going to be real special,” Acuna said. “Even though he is not playing, he’s going to be in the opposing dugout there. He already told me that he is going to be there.”