Back in the good old days when ballplayers assaulted groundskeepers and 72-year-old, gerbil-cheeked bench coaches instead of helpless female fans, the New York Yankees and Boston Red Sox played an extraordinary playoff series that did something previously unimaginable: It added new levels of animosity, intrigue and passion to a rivalry already bordering on insane.

Friday night at Yankee Stadium, the Yankees and Red Sox meet in the first of six games to be contested between the teams over the next two weekends, games that will go a long way toward deciding the American League East championship, which the Yankees have owned for six years.

But there is a strong argument to be made that the three games in the Bronx this weekend will not even be the most important series contested over those dates, for one simple reason:

With roughly 21/2 weeks left in the season, the Yankees (who lead the Red Sox by four games) and the Red Sox (who lead the Anaheim Angels by 51/2 games in the wild-card race) are both in excellent position to make the playoffs. It is entirely possible that by the time the teams meet again the following weekend at Fenway Park, both sides will be talking about magic numbers and postseason rotations.

"I see both teams making it," said one NL scout who has seen both teams in recent weeks. "The Yankees still have too many weapons, and the Red Sox are not going to keep playing .800 ball the way they've been doing. So I see it leveling off, with the Yankees holding on for the division and the Red Sox winning the wild card."

To find a series this weekend in which every win is crucial and every loss is devastating, one must go west.

In the AL West, where Oakland enjoys a two-game advantage over the Angels and a five-game cushion over the Texas Rangers, the Angels and Rangers meet for three games in Anaheim that might serve as the Rangers' final stand.

The Rangers most likely will be without reliever Frank Francisco, the league's rookie of the month for August, who is expected to receive a lengthy suspension for throwing a chair into the stands during a brawl between players and fans Monday night in Oakland, striking a female fan in the face.

Meantime, in the fascinating NL wild-card race -- which is simply the biggest free-for-all in the history of Commissioner Bud Selig's favorite creation -- two of the five teams bunched within three games of each other face off when the San Diego Padres visit San Francisco's SBC Park.

Two of the remaining contenders -- the Chicago Cubs and Houston Astros -- enjoy series against cupcakes Cincinnati and Colorado, respectively, while the weather-challenged Florida Marlins finally return home to face NL East-leading Atlanta.

To this point, the biggest mystery in the NL is how the Cubs, with all their powerful power-arms and all their offensive might (resulting in a plus-108 run differential), have let so many teams hang around in the wild-card race. But take note: The Cubs play 14 of their final 17 games of the season (beginning tonight) against the woeful Reds, Pirates and Mets, by far the easiest schedule of any of the wild-card contenders.

By contrast, the Giants, who lead the wild-card race by a half-game over the Cubs, face only playoff contenders or division leaders starting Friday through the end of the season.

If it is mystery how the Cubs have not pulled away, it is equally mysterious how the Giants -- with a team ERA (4.47 through Tuesday) that is higher than that of the Expos, Brewers or Mets -- have hung around this long. The answer, of course, is Barry Bonds, who has defined the middle word in Most Valuable Player.

"All we're doing," Giants closer Dustin Hermanson said following their win Tuesday night, "is clawing away."

Still, the collective angst of the Red Sox/Yankees kingdoms and the collective angst-ridden prose of the Boston and New York media machines will ensure that Yankee Stadium is the center of the baseball universe this weekend. Get used to it.

Between this weekend and next, plus a potential rematch in the AL Championship Series, there could be as many as 13 games remaining between the teams.

This weekend, Boston's Bronson Arroyo, Derek Lowe and Pedro Martinez face New York's Orlando "El Duque" Hernandez, Jon Lieber and Brad Halsey. (Pedro versus Brad Halsey? Is it any wonder the Yankees are worried what will become of them in October?) The series will either clarify the AL East picture, keeping both teams on a track for October, or turn the race into something else entirely.

"It's all going to come down to those games," Yankees Manager Joe Torre told reporters last week. "I think we've played enough games against the Red Sox this year with the people we have here to know that it's going to be fun for the people watching, and grueling for us."

Red Sox' Manny RamirezYankees'

Mike MussinaYankees' Tanyon Sturtze, center, battled David Ortiz, left, and Gabe Kapler of Red Sox in July 24 brawl that hiked rivalry between the teams to a new level.