MLB

Why this is the biggest Subway Series ever, hands down

Roger Clemens drilled Mike Piazza in the head in 2000 at Yankee Stadium, hours after Dwight Gooden walked off the street to beat the Mets at Shea Stadium.

If you are searching for the seminal moment in the 19 years the Yankees and Mets have been playing the Subway Series, July 8, 2000 is your date.

Nevertheless, should the search be for the most important skirmish, ignore the past. That’s because beginning Friday night at what should be a rocking Citi Field, the most meaningful regular-season series between the clubs opens with the first of three games.

The Yankees are attempting to stay close enough to the Blue Jays in the AL East so three games in Toronto next week provide them a legitimate chance to avoid the Best of the Losers tournament known as the one-game wild card. They trail Toronto by 3 1/2 games after the Blue Jays defeated the Braves in Atlanta on Thursday night. night’s Blue Jays result.

An eight-game lead over the Nationals, who lost Thursday to the Marlins, has the Mets on the doorstep of their first postseason appearance since 2006. Should that advantage dwindle to, say, five by Sunday, the Mets will hear plenty about the Collapse of 2007 when the Mets flushed a seven-game lead with 17 left.

And the Subway Series is being played later than ever in the season.

Carlos Beltran has played on both sides of the Subway Series.Charles Wenzelberg

“It’s going to feel like playoff baseball, and that’s probably a good thing,’’ said Yankees manager Joe Girardi, whose club copped two of three from the Rays prior to Thursday’s off day.

If the Yankees were playing the Orioles instead of the Mets, the significance of the games wouldn’t diminish because of where they stand in regards to the Blue Jays. Yet, that it’s Yankees-Mets adds a something to the pot.

“For us, they are huge games,’’ Yankees right fielder and former Met Carlos Beltran said. “Go there and hopefully win the series.’’

By now the Yankees have to know they can’t expect the Blue Jays to fade. While the Yankees wrestle with the Mets, the Blue Jays host the last-place Red Sox.

Taking two of three is a must if the Yankees want to stay in touch with the Blue Jays. Ditto for the Mets if they don’t want to hear about 2007.

With each club having something on the line and not having clashed since late April — when the Yankees took two of three at Yankee Stadium — there will be a different vibe in the Flushing air.

“I have been part of a lot of Subway Series, and this one has more meaning than most,’’ said Mets hitting coach Kevin Long, who held the same gig with the Yankees from 2007-14.

David Wright jokes with Derek Jeter during a 2012 Subway Series game.Charles Wenzelberg

“It’s fun, exciting, that’s why you play baseball. We will see if Mets fans come out a little more than they have in the past. When we played Washington, this place was rocking. I expect it to be the same as it was then.’’

Mets reliever Tyler Clippard, who made his big league debut as a Yankees starter in 2007 at Shea Stadium, believes having something to play for in the last month of the season adds juice to the deal.

“Meaningful games this late in the season brings better energy to each game,’’ Clippard said. “Fans are more involved and players can feel that, more of a playoff atmosphere.’’

David Wright understands what’s at stake for each club, and while players attempt to treat it like a Mets-Brewers game in June, it’s not going to happen.

“We never play them in September, so it’s a little odd,’’ the third baseman said. “The entertainment value is more for the fans and the city. As players, you try to treat it like another game. It’s difficult to do that because of the energy the fans have.

“You walk around the city and see the Yankees hats or the Mets hats and that gets you fired up. And at this time of the year, there should be more of that.’’

Additional reporting by Dan Martin