Mets catcher Gary Carter celebrates his 10th-inning walk-off homer on...

Mets catcher Gary Carter celebrates his 10th-inning walk-off homer on Opening Day at Shea Stadium against the St. Louis Cardinals on April 6, 1985.  Credit: AP/Ray Stubblebine

It’s well-known that the Mets have the best Opening Day winning percentage in baseball history at .655. The Mets have won 38 of their 58 season openers since being born in 1962.

Which victory was the best of all? That’s a tough question, but the nod here goes to the season opener at Shea Stadium on April 9, 1985.

The Mets beat the St. Louis Cardinals, 6-5, on Gary Carter’s walk-off home run off former Met Neil Allen in the 10th inning.

It was the future Hall of Famer’s first game with the Mets after an offseason trade that brought the catcher to Flushing from the Montreal Expos in return for Hubie Brooks, Mike Fitzgerald, Floyd Youmans and Herm Winningham.

The Mets under general manager Frank Cashen were assembling the squad that would go on to win the World Series in 1986. They won 98 games in 1985 and finished three games behind St. Louis in the NL East. There was no wild card in those days.

Carter already was a star when the Mets acquired him, but he was an under-the-radar star because he played for Montreal. Great things were to come in Flushing, and it started on Day One.

“Not only was he a great offensive and defensive player, but he had a flair for the dramatic,” former Mets pitcher Ron Darling said earlier this week. “Not everyone’s got it. Some people do and some people don’t. He certainly did. To do that in his first game, where he’s supposed to bring us across the finish line — against a guy [Allen] we had traded for Keith Hernandez — it was almost too good to be true.”

The Mets led 5-4 going into the ninth, but the Cardinals tied the score when Doug Sisk walked Jack Clark with the bases loaded.

Carter was the second batter in the bottom of the 10th after Hernandez, who had three hits and drove in two runs, struck out. It was Carter's sixth plate appearance; he was 1-for-3 with a double and twice had been hit with a pitch.

Carter swung at a hanging curve and hit it into the visiting bullpen in left-centerfield. Among the 46,781 jumping for joy in the stands was Carter’s wife, Sandy.

“That was a pretty exciting game, that’s for sure,” Sandy said this week. “I was at the game. I positively was there and I remember it being very cold and very full. It didn’t look like there was an empty seat in the house.

“Of course, the game wasn’t going too good before the extra innings. Gary came up to bat and I think there were even a few boos for him. His first taste of the excitable New York fans. In Montreal, they’re more low-key.

“He came up and I guess his juices were flowing. When he hit that home run, I mean, he always showed his excitement or his discouragement. He was an open book. He wore his emotions on his sleeve, so he was pumping his fists around the bases. I just couldn’t believe the excitement of the fans. That was the start of his 11th year as a big-leaguer. He had never had that many people saying, ‘Gary, Gary.’ The place just went nuts. I was chilled and crying. It was very, very exciting. It was an unbelievable way to start off your first game with the Mets.”

Sandy recalled that Carter had the right to veto the trade to the Mets as a 10-year veteran. He decided to  come to New York, and the rest is baseball history.

“Gary was shocked because we were just finishing building our home in Montreal, on the lake,” she said. “It was like, ‘What? We’re getting traded?’ Then [the Mets] rolled out the red carpet. We bought [a house] in Oyster Bay Cove. It was very, very fast. It was a big shock, but at that point, he was all-in.”