Enjoy the ride on this year's Subway Series, baseball fans. You may not see the likes of it again.

As part of Major League Baseball's move to two 15-team leagues next season, with the Houston Astros going to the American League West, the Yankees and Mets most likely will not play a pair of home-and-home, three-game series in the future.

Baseball wants to go to a balanced schedule, so the mish-mosh of opponents and dates that is interleague play will be replaced with a more orderly system in which one division plays another whole division in the other league. The matchups would rotate every three years.

Ah, but that doesn't mean baseball is going to kill New York-New York, Chicago-Chicago and other natural rivalries. Chances are good that the Yankees and Mets will play at least one three-game series every year, or possibly even two two-game series so both teams can sell out their ballparks.

"I've always thought there should only be three [games]," Yankees manager Joe Girardi said before the series opener Friday night at Yankee Stadium. "I think there should be a winner every year, for sure. I would actually be in favor of it."

After interleague play began in 1997, the Yankees and Mets played only one three-game series the first two years. That changed in 1999 when interleague play was expanded.

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"I've always been kind of old-school anyway," Derek Jeter said. "I liked it when we didn't even face the National League. When I first came up, that's how it was. You play in the World Series -- hopefully play in the World Series -- and you hadn't seen the team. I understand it's great for the fans and gives them an opportunity to see teams they don't normally see, but I kind of liked it the other way."

That ship has sailed, however, and regardless of whether the Yankees and Mets play three games or four or six, it probably always will be looked at as a measuring stick for the Mets.

That's true this year, as the surprising Mets brought a young team to the Bronx. It's the first Subway Series for Kirk Nieuwenhuis and first trip to Yankee Stadium for Lucas Duda. Mets manager Terry Collins said he was interested in seeing how his young players handled the unique pressure.

"To me, these are the games you grow in," Collins said. "These are the games you've got to learn how to play. If you want to win at this level and you want to play under the bright lights -- the brightest of lights -- you play in these games. You stick them in these games."

Collins said he'd "absolutely" like to see the Subway Series reduced to three games. For aesthetic reasons? No. Because playing the Yankees six times is tough on his club.

"Next year, who knows who is going to be in their lineup?" Collins said. "I know one thing: They'll be good. Every time we play them, we know we're going to face a tough lineup."