LOS ANGELES — Nine years ago, when the Dodgers faced off against the Mets in the 2015 NLDS, in the crowd at Dodger Stadium was a lifelong Dodgers fan who didn’t know it yet but would one day get to play October baseball for his hometown team.

That fan was Jack Flaherty.

The biggest question for the Dodgers going into the NLCS — just as it was heading into this postseason — was could their starters pitch well enough to give them a chance? And for Game 1 of the NLCS, Flaherty, who went to Harvard Westlake High School just 30 minutes away from Dodger Stadium, got the ball for L.A. with hopes of matching Yoshinobu Yamamoto and keeping up the momentum from the NLDS.

“You can’t really put it all into words, but the most important part was coming out here and setting the tone,” Flaherty said afterward. “But to be here and have some family in the stands and see some of them beforehand, it kind of lets you relax a little bit.”

Flaherty not only set the tone Sunday, but he also turned in his best start of the season in the Dodgers’ 9-0 victory over the Mets, twirling a two-hit shutout and giving L.A. a 1-0 series lead.

“This is certainly a childhood dream for him,” Dodgers manager Dave Roberts said. “You vet a guy, and you just feel that he can handle this market, handle pitching in a playoff game, starting a playoff game, so that wasn’t going to be a surprise for us. … The moment just isn’t gonna get too big for Jack.”

The Dodgers’ right-hander came out in Game 1 of the NLCS with a different feel than in his NLDS Game 2 start against the Padres. Flaherty grinded through at-bats against San Diego, but against the Mets, he got into a rhythm early, retiring the first nine hitters he faced.

On a night when he had very little traffic on the bases, the inning that could have changed the rhythm of the game came in the fourth. New York finally got something going with the top of the order when Francisco Lindor led off with a walk. Flaherty found a way to tightrope out of trouble, striking out the next hitter, Mark Vientos.

Two batters later, Pete Alonso walked to add pressure in the inning, but Flaherty was unfazed, as he would be the rest of the night. He induced a lazy flyout from Starling Marte to end the threat.

“I felt like I kind of figured some things out over the last couple days, just working through things,” Flaherty said postgame. “I felt like my stuff against San Diego was OK. But even in that game, I was able to get some outs, put a couple of zeros together, and then we just had to clean some things up. … Warming up before the game felt good, felt good yesterday. It just comes down to executing.”

The Dodgers’ key trade-deadline acquisition didn’t surrender a hit to the Mets until the fifth inning, when he allowed singles to Jesse Winker and Jose Iglesias to start the frame. But thanks to some horrible baserunning by Winker, New York spoiled its golden, two-on, no-out opportunity without scoring.

Flaherty then retired the final eight batters he faced, leaving the game after seven shutout innings having allowed just two hits, walked two batters and struck out six. The Dodgers, who have struggled with length from their starters, got their longest outing by a starting pitcher since Flaherty went 7 1/3 on Sept. 8.

“He gave us seven shutout [innings], set the tone,” catcher Will Smith said afterward. “We needed that. He really stepped up.”

“He was getting ahead with his fastball, and the slider and the slow curveball kept us off-balance,” Mets manager Carlos Mendoza said. “He tried to make us chase, which we did the first time through the order. He was just on.”

The Dodgers’ pitching seemed like their Achilles’ heel coming into the postseason, but it has been their biggest strength since Game 3 of the NLDS. The Dodgers tied the major-league postseason record by pitching 33 consecutive scoreless innings from Game 3 against the Padres through Game 1 against the Mets, tying the 1966 Baltimore Orioles in the World Series.

And they’ve done it without names such as Tyler Glasnow, Gavin Stone or Clayton Kershaw taking the baseball.

After Yamamoto’s start in Game 5 of the NLDS put a cap on the Dodgers’ triumph against the Padres, Flaherty’s dominance in Game 1 sent a clear message for L.A. in this NLCS.

“I think for us, we’re getting Jack at the perfect time, as far as he’s a veteran player,” Roberts said. “He’s been through a lot — highs, lows — and found his way back.”

Not to be forgotten amid the Dodgers’ dominant night on the mound, they also got a huge output from their offense. L.A.’s lineup exploded for nine runs on nine hits — without the help of the long ball. That included Mookie Betts’ 3-run double and Shohei Ohtani going 2-for-4 with an RBI and two runs.

But the Dodgers’ offense was the known commodity coming into October. If this team is going to continue getting strong performances from its starters and its bullpen, L.A. might be transforming into an unstoppable force at the best possible time.

“We have work to do,” Flaherty said postgame. “It’s Game 1. It’s a really good team over there. We’ll enjoy tonight, but we got a quick turnaround tomorrow. I’ll have fun watching these guys go out and compete and watching everybody around that comes out of the bullpen or whoever takes the ball and watching this lineup go to work.”