Yu Darvish #11 of the San Diego Padres pitches against...

Yu Darvish #11 of the San Diego Padres pitches against the Mets in Game 1 of the NL Wild Card Series at Citi Field on Friday, Oct. 7, 2022. Credit: Jim McIsaac

Pete Alonso’s first swing on the first pitch he saw in his first postseason game was a good one. He sent the offering from Yu Darvish deep down the leftfield line with two men on in the bottom of the first inning of Game 1 of the National League Wild Card Series at Citi Field on Friday night.

But even as the sellout crowd got to its feet to follow the drive, it was obvious it was going foul. It was not a three-run home run, just a long, loud strike.

Alonso swung through the next pitch and took the third one for a called strike three. It was the beginning of a night of frustration for the Mets in San Diego’s 7-1 victory.

Who knows if things might have gone differently if Alonso had connected a split-second later and kept that one fair. The Mets were trailing 2-0 and Alonso could have given them the lead.

Woulda, coulda, shoulda.

It’s not what the Mets wanted to be thinking, but the way Darvish shut them down for the third time this season had them shaking their heads as they head into Saturday night’s win-or-go-home Game 2.

“Tough game today for a lot of us,” said Alonso, who went 1-for-4 with two strikeouts. “But we’ve got to get back at it [Saturday].”

Darvish allowed two hits in seven shutout innings against the Mets on June 7 in San Diego. He allowed one run and four hits in seven innings on July 22 at Citi Field.

On Friday, Darvish again went seven. He allowed six hits and one run, which came on Eduardo Escobar’s fifth-inning homer with the Padres up 7-0.

Alonso struck out in his second at-bat, too, in the fourth inning. Darvish fooled him so badly that Alonso’s bat flew out of his hands on strike three. It flew to the netting covering the farthest corner of the Mets’ dugout.

“He located his pitches and he executed,” Alonso said. “It was as simple as that. He did a great job pitching to guys’ weaknesses.”

It’s not as if the Mets didn’t have chances. They went 1-for-11 with runners in scoring position. That one hit was a first-inning single by Jeff McNeil that sent Francisco Lindor from second to third just before Alonso’s first time up.

After Alonso struck out, Daniel Vogelbach hit a long drive into the rightfield corner that kept carrying but was caught by Juan Soto at the wall.

Jurickson Profar hit a similar ball off Max Scherzer in the fifth that hit the rightfield foul pole for a three-run homer.

It was that kind of night for the Mets, who won 101 games in the regular season and could go home on Saturday.

“We’ve been really good,” Alonso said. “And now we get to see what we’re made of.”