NEW YORK -- For the Mets, eight innings of frustration were about to melt away. Stymied throughout Wednesday evening by Shota Imanaga and the Cubs, the Mets found an opening when they put two men in scoring position with one out in the ninth. Jeff McNeil followed with a fly ball about two-thirds of the way down the left-field line -- perhaps deep enough to score Pete Alonso, perhaps not.

With the game on the line, Alonso put his head down and ran. As he did, Cubs catcher Miguel Amaya positioned himself to receive a throw, with half of one foot touching home. Eventually, Amaya shifted left to catch third baseman Nick Madrigal’s relay, covering more of the plate in the process. Alonso slid head-first, reaching between Amaya’s legs.

Everything converged at once. Home-plate umpire Charlie Ramos called Alonso out, unofficially ending the game as a 1-0 Mets loss. And then the chaos began.

As players from both sides watched from their dugouts, Major League Baseball’s replay review team examined two aspects of the play: Was Amaya illegally blocking home plate? And if not, did Alonso’s hand touch home before Amaya tagged him?

After close to four minutes of deliberation, replay official Derek Thomas issued his final rulings: No, and inconclusive. Alonso was ruled out and the Cubs’ victory was upheld, to the disbelief of many in the home clubhouse at Citi Field.

“I think they got the wrong call,” Mets manager Carlos Mendoza said.

Mendoza’s primary contention was with MLB’s regulation preventing catchers from blocking home plate without possession of the baseball. The so-called “Buster Posey Rule,” which is designed to minimize collisions, states that “the catcher is not permitted to block the runner’s path to the plate unless he is in possession of the ball, though blocking the path of the runner in a legitimate attempt to receive a throw is not considered a violation.” The rule adds that a runner can be ruled safe if the catcher was in violation.

“They send out a memo in Spring Training, what’s legal and what’s illegal,” Mendoza said of MLB. “It’s clearly on that email, that memo that we got, that catchers are not allowed to have their foot in front of the plate, on top of the plate. They cannot straddle without possession of the baseball. It was very clear that [Amaya] had his left foot on top of the plate without the baseball.”

MLB’s replay center issued an explanation on both aspects of the call, as is standard for all replay reviews, and it reads as follows:

“After viewing all relevant angles, the replay official definitively determined that no violation of the home-plate collision rule occurred. The catcher’s initial setup was legal, and he moved into the lane in reaction to the trajectory of the incoming throw.

“Additionally, the replay official could not definitively determine that the runner contacted home plate prior to the catcher applying the tag. The call stands, and the runner is out.”

Although Amaya never straddled home, half his foot was on top of it.

“I was 100% confident in myself [that I wasn’t blocking the plate],” Amaya said. “I gave him a lane, then they [had] the review exactly how I thought.”

Asked if he understood the rule, Mets catcher Omar Narváez replied: “I guess not anymore.”

“Everybody thought we got the call for us,” he added.

The ruling abruptly ended what, for eight innings, had mostly been a pitchers’ duel. Imanaga limited the Mets to three hits over seven scoreless innings, while José Buttó nearly kept up the pace with six innings of one-run ball. The Mets threatened in the eighth but did not score. Finally, in the ninth, they found life when Cubs closer Héctor Neris hit Alonso with a pitch and J.D. Martinez followed with a booming double.

The Mets had no position players available to pinch-run for Alonso, and Mendoza was forced to use his bench early when Francisco Lindor exited the game after two innings with flu-like symptoms and was replaced by Joey Wendle at shortstop.

With one out and first base empty, the Cubs elected to pitch to McNeil, who hit an opposite-field fly 272 feet down the left-field line. Alonso dashed home. Ramos called him out. Mendoza exploded onto the field to challenge.

While both teams waited for the ruling, Alonso watched a video replay on the center-field scoreboard. Helmet still in hand, he spread both arms wide to signal that he believed he was safe.

“Initially as it happened, I thought I snuck my hand in there,” Alonso said. “But the call said I was out, so I was out.”

After the game, several of Alonso’s teammates still believed he was safe. Amaya contended that he did nothing wrong. Mendoza said he looked forward to hearing more from MLB on the matter, though both he and Alonso acknowledged that the time to argue had already passed.

“I hustled as hard as I could,” Alonso said. “I made the best slide I could possibly make. The umpire said I was out, so I was out.”