BOSTON — Six weeks of foreplay leads to the biggest regular-season nirvana in baseball tonight.
That’s when the Yankees and Red Sox collide in Fenway Park for the first game of the 2010 season.
It’s the first of 18 games between the bitter AL East rivals, and not since 2001 have the Yankees opened a season as the defending world champions.
Familiar names dot the rosters of two of the best teams in baseball, but each made significant moves.
The Red Sox added bulldog right-hander John Lackey, center fielder Mike Cameron, third baseman Adrian Beltre and shortstop Marco Scutaro. Jacoby Ellsbury moves from center to left and replaces Jason Bay.
The Yankees countered by trading for Javier Vazquez and Curtis Granderson, and signing Nick Johnson after saying so long to Johnny Damon and Hideki Matsui.
Tonight in New England’s living room, we get a tiny sliver of information on who made the better moves and if there is something to being the defending champs.
“The bull’s-eye might be a little bigger, but we are the Yankees, and people are always ready for us when we show up. Nothing changes,” Alex Rodriguez said.
When it comes to Fenway, there will be zero changes regarding Red Sox fans, a group that has to ice its lungs after hurling abuse at the Yankees, no matter if it’s Opening Day or the middle of May.
CC Sabathia, who won 19 games last year, will face 17-game winner Josh Beckett in a test of aces.
Without Damon hitting between Derek Jeter and Mark Teixeira, and Matsui, the World Series MVP, the Yankees are starting Brett Gardner in left and have transformed Johnson from a first baseman to a DH. He will hit second.
“It might take a few weeks to find an identity,” Teixeira said. “We may run a little more with Granderson and Gardner. Most of the team is back. I don’t think we will miss a beat.”
Gardner, who will bat ninth and Granderson, who will hit seventh, provide the Yankees with base-stealing threats the likes of which the Red Sox haven’t seen in pinstripes in years.
Andy Pettitte has been part of the rivalry since 1995 and has worked Fenway 17 times. Still, the blood never stops flowing a little faster.
“The atmosphere is always great and when you walk out of the dugout you feel the buzz,” said Pettitte, who pitches Wednesday night. “That doesn’t get old.”
Like Pettitte, Mariano Rivera has been sloshing through the always wet and moldy runway that leads from the visitors’ clubhouse to Fenway’s third-base dugout, which is slightly bigger than a shoebox. And he embraces the extra juice at the start of the season.
“If you have to open the season, why not with the Red Sox?” said Rivera, who begins his 16th major league season with 526 saves and trails all-time leader Trevor Hoffman by 65.
Rivera, 40, is jazzed about those dressing near him.
“We have a great team, we have to do our job, but we have a great team,” Rivera said.
Of course, that remains to be seen. And three games in Fenway won’t define that. Remember the Red Sox won the first eight games last year and the season series ended 9-9.
It’s Opening Day, the Yankees at Fenway. It’s only right that there are no other games today.
george.king@nypost.com