In the perfect world, what we have this weekend is a foreshadowing. Five years have passed since the Red Sox and Yankees met in the historic 2004 American League Championship Series. Many of the names have since changed, but the story remains the same.

Boston meets New York.

May the best city win.

And so, after a season’s worth of games and maneuvers, the Red Sox and Yankees today are precisely where many expected them to be: atop the American League. Boston and New York will begin their final regular season series of the year tonight with the two best records in the AL, seemingly on a collision course for October. The Yankees already are in the playoffs. Certainly, the Red Sox will be soon. And if all goes according to script, the Red Sox and Yankees will resume acquaintances again in the middle of next month for the right to go to the World Series.

Of course, the Los Angeles Angels may have something to say about that. So may the Detroit Tigers or, perhaps, the Minnesota Twins. But after a season of extremes in which the Sox and Yankees have taken turns beating up on one another, Boston and New York look relatively even entering the only time of the baseball calendar year that truly matters in either city.

In retrospect, this year has broken down into three pieces:

PHASE I
(Opening Day through June 24)

Back then, the Red Sox looked like the obvious class of the American League, if not all of baseball. They had a season-high, five-game lead in the American League East. They were 44-27 -- New York was 39-32 -- with a deep pitching staff and productive offense. While the Red Sox and Yankees had scored a virtually identical number of runs -- New York 386, Boston 382 -- the Red Sox had a decisive edge in ERA, 4.12 to 4.62 while the remodeled Yankees struggled to find their stride.

The Sox were a perfect 8-0 against the Yankees to that point. Many of us openly wondered whether New York’s acquisitions of CC Sabathia, Mark Teixeira and A.J. Burnett would ultimately mean anything at all.

PHASE II
(June 25 through Aug. 23)

As if experiencing a breakthrough, the Yankees caught fire. While the Red Sox settled into a problem-plagued, 52-game stretch during which the Sox went a perfectly mediocre 26-26, the Yankees caught fire. New York went 39-14 over a 53-game span to make up a whopping 12.5 games in the standings and assume control of the division. They have not relinquished it since. During this span, New York outscored the Red Sox by 43 runs and the pitching completely flip-flopped -- New York posted a 4.02 ERA, Boston 4.51 -- while the Yankees went 6-1 in head-to-head meetings between the teams.

With his club losing ground at an astonishing rate, general manager Theo Epstein went about the business of fortifying his roster. While relying on internal pitching depth to augment the starting rotation, the Red Sox improved their lineup, defense and bullpen by acquiring, in order, Victor Martinez, Alex Gonzalez and Bill Wagner.

PHASE III
(Aug. 24 to present)

A funny thing has happened in the last month or so: the Yankees haven’t slipped so much as the Red Sox have caught up. During this span, the while scoring a virtually identical number of runs -- Red Sox 172, Yankees 171 -- the Red Sox have gone a major league-best 21-8 while New York has gone 19-10. The Boston pitching has stabilized. While the Yankees experienced some instability in their starting rotation, the emergence of Clay Buchholz fortified a Boston staff that has a 3.98 ERA in the last month. (The Yankees’ ERA is 4.23.)

As a result, there is the very real possibility this weekend that New York will clinch the AL East while the Red Sox similarly wrap up a playoff berth, a fitting bit of symmetry given the way this season has evolved.

Since the last time the Red Sox and Yankees have met in the postseason, a great deal has changed. Boston and New York have substantially modified their rosters, the likes of Josh Beckett, Jon Lester, Sabathia and Burnett being thrust into a rivalry that may be unparalleled in all of sports. The identities of both franchises have been altered -- on the field and off -- and new tension exists. Kevin Youkilis has Joba Chamberlain to despise. Joe Torre is gone. Johnny Damon wears pinstripes. Alex Rodriguez has handed off his role as the rivalry’s central to figure to Teixeira, the latest Yankees who might have been a Red Sox. Meanwhile, there are still enough holdovers from the old days -- Jorge Posada, Derek Jeter, David Ortiz, Jason Varitek -- to remind us that New York and New England are forever connected by more than just Interstate 95.

This weekend, in the big picture, the games between the Red Sox and Yankees really won’t mean much.

But as the teams bid farewell to one another Sunday, we can all hope that they will soon meet again.