PHILADELPHIA — Long before spring training even started, the Boston Red Sox and Philadelphia Phillies were favorites to play each other in October.

Here comes an early taste.

Although the calendar says it’s June and more than half the games remain, this week’s Red Sox-Phillies series is being billed as a World Series preview.

“It’s going to be a great series, fun to watch, fun for everybody,” Phillies slugger Ryan Howard said. “It should be a good, exciting series. We want to win every game. We know we’re going to have to step it up for these guys.”

The teams will open a three-game set at Citizens Bank Park tonight with Cliff Lee (8-5) facing Josh Beckett (6-2). The Phillies have the best record in the majors at 49-30. The Red Sox, despite an awful start, are third-best at 45-32, just a half-game behind the New York Yankees in the AL East.

“Right now, you just look at it as another series but in the back of your head you’re like, ‘I might be facing these guys in the playoffs,”‘ Red Sox slugger David Ortiz said.

When Lee spurned the Yankees and took less money to come to Philadelphia last December, the only people happier than Phillies fans were Red Sox ones.

“When he signed (with the Phillies), I was happy,” Red Sox Manager Terry Francona said. “But he’s on a roll now. Those are fun games to play. You kind of go in knowing you’re not going to knock it around the ballpark, but those sure are fun games to be a part of.”

Lee has thrown consecutive shutouts and hasn’t allowed a run in 23 innings. Beckett leads the majors with a 1.86 ERA, but hasn’t pitched since tossing a one-hitter against Tampa Bay on June 15 because of the flu.

The matchup features the best pitching staff in the majors — the Phillies lead the league with a 3.05 ERA — vs. the best offense — the Red Sox lead with a .277 average.

The trio of Lee, Roy Halladay (10-3) and Cole Hamels (9-4) have carried the Phillies so far. Injuries to Roy Oswalt and Joe Blanton have hurt the back end of the rotation.

Halladay won’t pitch against the Red Sox. Vance Worley (2-1) goes on Wednesday and Hamels will move up a day and pitch on regular rest Thursday afternoon. John Lackey (5-6) takes the mound in the middle game for Boston and Jon Lester (9-4) faces Hamels in a duel between two of the top lefties in baseball.

“I see it as Phillies vs. Red Sox,” Howard said. “I don’t try to get into offense vs. pitching, or all of that extracurricular stuff. That’s for ya’ll. I’m out on the field and that’s what I’m into, what’s going on in the game.”

The Red Sox are missing Carl Crawford, who is out with a hamstring injury. Crawford, a top free-agent acquisition from Tampa Bay, played a key role in Boston’s turnaround after slumping badly and hitting just .155 in April. Ortiz also won’t be in the lineup because the designated hitter isn’t used in NL parks. Big Papi likely will be relegated to pinch-hitting duties.

Still, the Red Sox have plenty of pop. Adrian Gonzalez leads the AL in hitting (.361) and RBI (71). Kevin Youkilis (.275, 11, 55) is having another solid season.

The Red Sox are 26-17 against the Phillies and took 4 of 6 meetings last year. They’re 11-4 in Philadelphia’s cozy, hitter-friendly ballpark.

“Anytime the Red Sox come in, it’s big for us,” Phillies Manager Charlie Manuel said.