Cubs edge Mets 1-0 with game-ending double play by Ian Happ, Nick Madrigal and Miguel Amaya

Frank Franklin II/AP Photos

NEW YORK — Fans in the stands grew increasingly restless as the review dragged on. The angle from behind the plate played on the giant Citi Field video board, and Mets fans erupted in cheers. Then the next angle, from the first baseline, sent Cubs fans into an excited frenzy.

Cubs left fielder Ian Happ had caught a fly ball and fired to third baseman Nick Madrigal, who relayed it home to catcher Miguel Amaya, who tagged Mets base runner Pete Alonso for what was called a game-ending double play. But the Cubs’ 1-0 victory was on hold until the Replay Center finished looking over the relevant angles.

“Not great. Didn’t love it,” Happ said, cracking a smile. “That’s a long process, just waiting and waiting and waiting.”

At long last, the decision came down. The Cubs had pulled off the narrow victory.

A combination of great pitching and staunch defense made the only run of the game enough to put the Cubs on top.

Lefty Shota Imanaga had arguably the best start of his already impressive young career, tossing seven scoreless innings and limiting the Mets to three hits.

In six starts, he’s held opponents to no earned runs four times. When he exited Wednesday, Imanaga’s 0.78 ERA led all qualified pitchers this year. It’s also the fourth-lowest mark by a pitcher in his first six major-league starts since 1913, when earned runs became an official stat in both leagues.

“Just seven really strong innings,” manager Craig Counsell said. “Wasn’t in trouble, really. It was crisp, it was clean.”

The Cubs offense was relatively quiet for the fifth straight game. When rookie Matt Mervis hit a leadoff double in the fifth inning, he was just the second runner the Cubs had put in scoring position. He reached third, and Pete Crow-Armstrong hit a sacrifice fly to the warning track for the go-ahead run.

The game still stood at 1-0 in the bottom of the ninth inning, when right-hander Héctor Neris took the mound for the save. With one out and runners on second and third, Jeff McNeil hit a fly ball down the left field line.

“It was trying to get around it as best I could,” Happ said. “It’s always a little bit harder going towards the line. Trying to get it out of my hands as quick as possible, that was my goal there.”

Madrigal thought Happ might throw all the way home. But Happ made the split-second evaluation that he wasn’t behind the ball enough to pull that off and that a relay would get the ball to plate quicker.

“When I saw him throw it real low to me – I mean, he threw it so good – I had an idea that maybe we might have a chance,” Madrigal said. “So I just went for it.”

Amaya had already set up his lane, inside the basepath, his left foot on the edge of the plate. He fought the temptation to slide it across, and as he felt the ball hit his glove, he dropped to a knee and tagged Alonso on the shoulder.

Amaya turned to show home plate umpire Charlie Ramos the ball in his mitt, and Ramos punched the air without hesitation.

The Mets’ challenge halted the Cubs’ celebration in its tracks. And the review took so long in part because it covered two different aspects of the play: Whether Amaya blocked the plate, and whether Alonso got under the tag.

The replay official “definitively determined” that Amaya hadn’t committed a violation because when he did move into the lane, he was following the trajectory of Madrigal’s throw. And there wasn’t definitive evidence that Alonso touched the plate before the tag. So, the call stood.

“I was 100% sure from what I felt and what we did,” Amaya said. “And they made the right call.”