WASHINGTON — Noah Syndergaard went from bruised and bloodied to delivering a smackdown of his own Monday.

The worst start of his career never had a chance to snowball into something significant, as Syndergaard dominated the Nationals and watched his Mets teammates put a touchdown on the scoreboard.

In a Labor Day picnic, the Mets rolled to a third victory in four games, 7-3 at Nationals Park. The Mets remained four games behind the Cubs in the race for the NL’s second wild card.

Syndergaard got destroyed by the Cubs in his previous start, allowing a career-worst 10 runs over three innings. He was the complete opposite against the Nationals, allowing only three hits over seven shutout innings in which he struck out 10 batters.

“I had to find a happy medium between starts, because when you have a start like [against the Cubs], those four days in between are long,” Syndergaard said. “I just wanted to get out there and work, work, work as much as I could to make sure that never happened again. It was kind of unfortunate to have that horrible of an outing. You have just got to embrace it and see it as a blessing to get better.”

The double-digit strikeout game was Syndergaard’s third of the season and the 17th in his career. Syndergaard retired 16 straight batters after allowing a leadoff single to Trea Turner to start the game and allowed only three base runners in the seven innings.

“You could see it in [Syndergaard’s] eyes, he felt like that in between starts, he wasn’t happy with what happened the last outing and comes out today and steps up huge,” manager Mickey Callaway said. “Ten strikeouts, no walks, 90 pitches, seven innings, he did everything he needed.”

The Nationals entered with nine victories in 10 games to fortify their lead for the NL’s top wild-card spot. That lead had swelled to 4 ½ games over the Cubs as play began. At home the Nationals have been particularly strong, with a 40-28 record.

The Mets showed little effect of playing a Sunday night game in Philadelphia and then traveling here for a 1 p.m. start.

“One thing about this team, we’re resilient,” J.D. Davis said. “I went to bed around 3:30 or 4 o’clock, I am sure guys went a little bit later. To turn around and get this Game 1 it’s huge, especially with having Max Scherzer [on Tuesday] and [Anibal] Sanchez, a veteran guy that knows what he is doing out there.”

Davis led the offensive surge by going 3-for-5 with two RBIs. Jeff McNeil homered and Brandon Nimmo reached base three times. Wilson Ramos did not play, keeping his hitting streak at 25 games.

The Mets turned the game into a runaway in the fourth when they sent nine batters to the plate and scored five runs, knocking out Joe Ross in the process.

McNeil snapped a career-longest hitless streak a 15 at-bats by stroking a two-run homer that gave the Mets a 4-0 lead, and a hit parade followed: Pete Alonso and Michael Conforto each singled before Davis delivered a two-run double. Nimmo’s ensuing RBI double buried the Nationals in a 7-0 hole.

But Syndergaard wasn’t about to get complacent.

“Rene [Rivera] came to me between innings and said we’re going to continue to go about it as if it’s a 0-0 ballgame,” Syndergaard said.

Joe Panik smashed an RBI double in the second after Davis had singled and Nimmo walked. Rivera followed with a bloop RBI single that gave the Mets a 2-0 lead.

The Nationals got their runs in the ninth on Asdrubal Cabrera’s three-run homer against Tyler Bashlor.

“[Syndergaard] is a great pitcher and has been on a great roll,” Callaway said. “So you take that one clunker out and he’s been unbelievable.”

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