Phillies vs. Mets in September — and it matters for the first time since 2008. Let the fun begin.

The bases were loaded with one out in the ninth inning. Both managers had emptied their bench and exhausted their bullpen. A packed crowd stood and roared, hanging on every pitch.

October in South Philly?

Actually, it was June. In London.

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It also marked the last time the Phillies and Mets got together. And any notion then that the long-standing rivals’ seven matchups in September would be meaningful for both teams seemed as far-fetched as President Biden not running for reelection.

Because while the Phillies were 45-19, tied for the best start in franchise history, Mets owner Steve Cohen fielded questions before the game about how much of his roster would be sold off at the trade deadline.

So consider this weekend a pleasant late-season surprise.

The Phillies overcame a midsummer swoon and are closing in on their first division title since 2011. They have won three games in a row — and 14 of the last 18 — to reduce their magic number to nine.

And here come the Mets, on a 52-30 heater since London — the best record in baseball during that span — with a one-game lead over the Braves for the last wild-card spot in the National League.

“They’re rolling, no doubt,” Phillies right fielder Nick Castellanos said. “I definitely don’t think it’s going to be the same team that we saw over in London.”

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Indeed, the Mets still weren’t committed then to Mark Vientos at third base; he has 24 homers now, 19 since London. Veteran infielder José Iglesias only recently had come up from triple A; he’s batting .317, when he isn’t performing the pop song that has become the Mets’ anthem. Sean Manaea has a 2.72 ERA over his last 15 starts.

But the biggest difference is the play of Francisco Lindor. Through the London Series, the star shortstop was batting .235 with 10 homers and a .710 OPS. Since then: .295, 21 homers, .925 OPS.

Two years after the Mets won 101 games with most of their current core of position players, Lindor has lifted them back into contention — and himself into the MVP conversation, alongside unicorn slugger Shohei Ohtani. And it has added an overdue buzz to these seven games in the next 10 days — three at Citizens Bank Park this weekend, four at Citi Field next Thursday through Sunday.

Baseball around here is more fun when the Phillies and Mets are good at the same time. The problem is, it happens as infrequently as a comet sighting.

When the Phillies won the World Series in 1980, the Mets finished 24 games out of first place. When the Mets went all the way six years later, the Phillies were 21½ games back. In 63 seasons of coexistence as major league franchises, this will be only the 10th — repeat: 10th! — instance of them having winning records in the same year.

Historically, the Phillies and Mets haven’t been heated rivals separated by 112 miles of interstate as much as ships passing on opposite ends of New Jersey.

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Now, let’s be clear: These games mean considerably more to the Mets. Fangraphs gives them a 56.9% chance of making the playoffs in a race that qualifies as a toss-up with the Braves (56.1%). Both could get in, but that would mean bumping the Padres or Diamondbacks, who are 2 and 1½ games clear, respectively, of being outside the playoff picture.

The Phillies have a 99.4% chance of winning the division, according to Fangraphs, 96.8% to get a first-round bye. Their ticket to October is nearly punched.

But the Phillies and Mets haven’t squared off this late in a season while occupying first and second place since … checks notes … 2008. So we’ll take what we can get, while also recalling September 2007, the apex of Phillies-Mets drama.

A history lesson, if you’re younger than, say, 24 or 25: The Mets led the NL East by seven games on Sept. 13 (we’ll wait while you peek at the calendar) before getting swept at home by the Phillies, the start of a 5-13 free fall. The Phillies, meanwhile, finished on a 13-4 kick to win the division on the season’s final day and turn Jimmy Rollins’ famous “team-to-beat” boast into a prophecy.

“I’ve gotten to know Jimmy really well over the years — couldn’t be a better guy ― but back then I truly hated him,” former Mets third baseman David Wright said in a recent phone conversation. “When you have your team leader publicly come out and be that confident, and then back it up with the season that he had, incredibly impressive.

“That’s what made that rivalry so great. That’s why I loved going to Philadelphia, and that’s why I loved when Philadelphia came to New York. I loved that intensity, and I loved that feeling. I wanted to beat them so badly that it probably took me out of my game a little bit. But I loved every second of those games because they had that core, we had our core, and I just truly enjoyed it.”

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But that was a long time ago. And although it would take a hide-your-eyes, 1964-style Phillies collapse to give the Mets hope of a reverse 2007, it’s enough that the next 10 days will have implications for both teams.

The Phillies could clinch the NL East title in New York (if they don’t take care of business earlier next week in Milwaukee). The Mets could solidify their wild-card chances. Or the Phillies could knock them out.

“They’ve been playing good baseball as of late. So have we,” Castellanos said. “I’m excited.”

Join the club.