PHILADELPHIA — Luis Severino reached back.

A bulldog of a starter who remained healthy all season for the first time since 2018 had a little bit more left in the tank in his 33rd turn of the year.

In his sixth inning of work, the righty knew the threat Bryce Harper posed and delivered a 99-mph fastball, the hardest pitch of his afternoon and the third-fastest pitch he has thrown all year.

Harper’s best, though, was better.

Severino was excellent for five innings and hit hard twice in the sixth, once by Harper, as part of a 7-6, Game 2 loss to the Phillies at Citizens Bank Park on Sunday.

Severino rolled for five innings until he abruptly halted in the sixth.

Manager Carlos Mendoza trusted his starter the third time through the Phillies lineup partly because he just trusted him, he said, and partly because he had limited options in an overworked bullpen.

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In the game-changing inning for Severino, he recorded two quick outs before Trea Turner singled.

Pitching coach Jeremy Hefner visited Severino with a message of “being careful” with Harper, Severino said, and not giving him much to hit.

On Sept. 14 in Philadelphia, Harper had upturned Severino’s outing by blasting homers in the fourth and sixth.

Severino was not careful enough, and it happened again: Harper was ready for an amped-up Severino, turning 99 mph down the middle into a titanic shot that bounced off the bushes in center an estimated 431 feet away.

“I was trying to go up and away,” Severino said. “Trying to throw a purpose pitch away, but it went to the middle.”

A sleeping, sellout crowd was jolted awake and still deafening two pitches later, when the volume was cranked up again.

Nick Castellanos demolished a sweeper that got too much of the plate 425 feet to left-center, tying a game that the Mets would lose with Edwin Diaz and Tylor Megill on the mound in the eighth and ninth.

Severino finally escaped the inning, concluding a six-inning, three-run outing in which he allowed as many hits in the sixth (three) as he had in the first five innings combined.

“The way he was throwing the baseball, I don’t care about third time through [the order], he’s pitching really well,” said Mendoza, who felt his hands were tied by the depleted bullpen. “And … if I pull him early, then they’ll have to cover 12 outs, and that wasn’t the case today.”

The outing was a challenging one for Severino not just because of his growing workload but because he had faced this Phillies lineup twice in mid-September, the familiarity generally favoring the batters.

But for five innings, it had seemed the advantage belonged to the pitcher. Severino was prepared for an offense that, while mighty, is not terribly disciplined.

The Phillies chased pitches out of the strike zone the seventh-most in baseball this season, and Severino lived on the edges and off the plate.

He was mostly untouched until he threw his fastest pitch of the game and watched it get obliterated.

“Doesn’t matter how hard you throw it,” Severino said. “They’ll hit it back even harder.”