Matt Harvey arrived at Citi Field Thursday afternoon wearing a stylish trench coat worthy of a stroll through SoHo. Hours later, when the Mets righty took the mound, he left the top two buttons of his blue uniform top undone.

He seemed determined to make his first start since thoracic outlet surgery look like business as usual. But in a 6-2 victory against the Braves, it was clear that things were different. They’ll have to be, at least for a while.

“I knew my body felt good,” Harvey said after winning his first outing since July 4. “It was just about executing pitches and getting people out.”

If Harvey weathers this storm, if he can tame big-league hitters while he waits for his fastball to come all the way back, he will follow the formula that he laid out last night. That’s when he leaned on a pitcher’s most trusted weapons.

In 6 2⁄3 innings, Harvey changed speeds and used his slider to keep the Braves honest. He allowed two runs on solo shots by Matt Kemp, both on 94-mph fastballs that caught too much of the plate. These were the only mistakes.

The only other hit Harvey surrendered was on a swinging bunt by Nick Markakis, who was fooled so badly on a curveball that all he could do was dribble it down the line with the end of his bat. This was more emblematic of a night in which Harvey looked comfortable as a slightly diminished version of himself and lifted the Mets to victory in their first series of the season.

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“It’s executing pitches,” Harvey said. “I was able to locate the fastball away, and throw good sliders and changeups when I had to.”

Strikeouts, once a staple of Harvey’s starts, were relatively scarce. He got only four punchouts, a reflection of his reliance on sliders and changeups. But aside from Kemp, the Braves managed only soft contact.

“Matt Harvey can pitch as good as anybody when he’s 93-95,” manager Terry Collins said. “And he showed it tonight.”

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Kemp’s homer in the fifth gave the Braves a 1-0 lead. To that point, the Mets had scored in just two of the first 24 innings they played in 2017. Then they came to life.

Travis d’Arnaud ripped a double into the gap in left-center to give the Mets a 2-1 lead. In the sixth, lefty-killer Wilmer Flores lived up to his reputation with a two-run blast, his first of the year, to make it 4-1.

In the seventh, after the Braves cut it to 4-2 on Kemp’s second homer, the Mets answered with two more runs. They had scored in three consecutive innings, easing concerns of an offense that had stumbled from the gates. But Collins said he figured that the line would break out. It was Harvey who needed to quell any lingering questions.

“The focus was on Matt pitching well tonight,” Collins said.

When Harvey began spring training, his fastball hovered in the low 90s, and the Mets braced for a long wait until the end of May. That’s when they could expect an uptick in velocity following surgery. But his outings improved, his velocity gained life.

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Harvey’s fastball touched 95 mph last night, still not in the high 90s but good enough to challenge big-league hitters. “This game is about location and not velocity,” said d’Arnaud, who noticed a change in demeanor.

Last July, as Harvey’s nightmarish season was nearing its end, he could barely feel the baseball in his hand. Thoracic outlet syndrome had robbed him of this sensation. Only the removal of a rib would bring it back.

But Thursday night Harvey pitched with a precision he couldn’t achieve last season. He was pulled after 77 pitches, with two outs and a two-run lead in the seventh. It was a conservative move by Collins, who was glad not to push his luck. The crowd offered a warm ovation, a sign that Harvey had done enough.

“Just being able to have feeling in my hand,” he said, “that’s the biggest thing.”