In what was effectively the first postseason game of 2015, the fans of New York had a brand new topic to debate: Who needs this first September Subway Series more? The Mets, who are desperately trying to hold off ghosts of 2007 or the Yankees, who are desperately trying to catch the Blue Jays?

We will know for sure when the real postseason gets here. What was clear Friday night was that the Mets were the ones who took a huge first step. They flexed their new power, with Lucas Duda and Daniel Murphy each hitting a home run against their rivals' best pitcher, Masahiro Tanaka. The Mets won the opener of a unique and important series, 5-1, at Citi Field.

The calendar and standings said it was definitely different, even by Subway Series standards. "I think it's always intense, especially here," said Duda, who also had a double.

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What made it memorable for the Mets was when Juan Uribe added a pinch-hit, two-run home run in the seventh against Chasen Shreve, evoking a chorus of "Let's go, Mets" on a September night that felt like October. Steven Matz (4-0), who grew up in Stony Brook rooting for the Mets during a Yankees era, pitched well in the biggest game of his young career, allowing only one run in six innings.

"That was the most fans I've ever pitched in front of and the crowd was pretty electric," Matz said. "It was pretty fun, though. Once I stepped onto the mound, it was a lot of fun."

The Mets maintained their eight-game lead over the Nationals in the NL East and reduced their magic number to eight.

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The Yankees lost the game and ground in the standings to the Blue Jays, who increased their AL East lead to 4 1/2 games by beating the Red Sox behind Matz's fellow Long Islander Marcus Stroman. With Alex Rodriguez (no DH in a National League park) and Brian McCann (rested) not starting, the Yankees didn't have the punch to keep up with their neighbor. They moved a step closer to the wild card despite making it interesting by bringing the tying run to the plate in the ninth.

"We've got to take advantage," said Chase Headley, who struck out to end the game against Jeurys Familia. "They have good arms, but we had opportunities."

For the Mets and their fans in a crowd of 43,602, it was an opportunity to enjoy a sigh of relief. It was a bounce-back night following a pair of losses to the Marlins, which temporarily raised faint echoes of the September collapse eight years ago.

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The Mets are deeper now, in talent, confidence and experience. Maybe it was no coincidence that the big hits came from veterans. "That," Terry Collins said, "is what your veteran guys are supposed to do."

On one hand, it was extraordinary to have a regular-season Subway Series game so late in the season. It stood out in a rivalry that always stands out. On another level, the game was so important to three races (AL East, AL wild card, NL East) that the New York-New York aspect of it didn't deserve top billing.

Still, as strange as it was to see them together in September, familiarity was the theme. Each club knows all about the other, just as they did the first time they met for real, in 1997. Back then, the Yankees catcher said: "I know how important it is for the Yankees to beat the Mets. We all know it."

That catcher, Joe Girardi, now the Yankees manager, said Friday night: "They're swinging the bat as well as anyone since Aug. 1. They have added young pitching that is very talented. They've gotten better and that's reflected in their record."