Weekend Series Can Make or Break Yankees and Red Sox Playoff baseball in August? Aside from the weather, it certainly feels like it.

The Yankees and Red Sox meet in the biggest series of the season to date, a series that has more than just bragging rights on the line. A series that could decide the fate of these two teams for the 2009 season.

Before 2007, there used to be a series like this one between these two teams at some point every season. Last summer, the Yankees had the type of injury bug that the Mets are experiencing this season, and in '07, the Red Sox ran away and hid with the division, protecting their lead all the way until October, even with a late surge by the Bombers in the final weeks of the year.

In 2006, the Yankees went to Fenway Park leading the Red Sox by 1 1/2 games and left leading by 6 1/2 games, virtually ending the Red Sox' season.

In 2005, the Yankees trailed the Red Sox by four games on Sept. 10 before rallying to clinch the division in Boston in Game 161 of the season.

Trailing in the division by 8 1/2 games in 2004, the Red Sox used a brawl at Fenway and a walk-off win in late July to rejuvenate their season en route to their first world championship in 86 years.

And the list goes on …

Year in and year out, the success and failure of the Yankees or Red Sox in a given season can be traced back to a meaningful series between the two teams following the All-Star break. And this weekend has the chance to be that series for 2009.

The Yanks' 0-8 record has been thrown around every day since the teams last met on June 11. Walk-off wins, comeback wins, extra-inning wins, blowout wins, you name it … the Red Sox have used it to put away the Yankees.

With three sweeps of the Bombers this season, an unlikely fourth one would be demoralizing to the red-hot Bombers. But a sweep on the Bombers' end would put the Red Sox in a devastating hole with 50 games left to play.Weekend Series Can Make or Break Yankees and Red Sox

This weekend, the Yankees have a chance at redemption. A chance to increase their lead in the East to as many as 6 1/2 games, or a chance to blow their lead completely and trail the Red Sox by 2 1/2 games following Sunday night's game. There are a number of different ways the standings could look come Monday morning, but it all begins with Thursday night's series opener.

With Joba Chamberlain on the mound against John Smoltz, the Yankees hold an enormous advantage. They enter the series on a three-game winning streak with the best pitcher in baseball since the All-Star break on the mound and return home where they are 35-17. With seven lefties in the lineup against Smoltz, who has allowed a .397 average to lefties and posted a 7.12 ERA, you would think the Yankees would win the opening game with relative ease. However if they fall to 0-9 on Thursday, things could spiral out of control for the Bombers with Josh Beckett taking the mound for the Red Sox on Friday.

Baseball fans in the Northeast tend to have football mentalities when it comes to their teams, and most of the season it is a little much. But not now, not in August with the division on the line in a pennant race that is likely to go down to the wire.

Nearly every season, a series between the two AL East powerhouses defines both clubs' seasons. Sometimes it comes in late July, sometimes in September. This season, it comes in August.