They clinched the AL wild card to assure a berth in the 2004 post-season. They swept the Anaheim Angels in the first round to enter the ALCS against the Yankees for the second straight year.
As Boston entered the fourth game of the ALCS, they had fallen three games behind the Yankees, including a Game Three loss by the score of 19-8.
Trailing 4-3 in the 9th inning of Game 4, they embarked upon an unprecedented (in Major League Baseball) comeback from a three-game deficit to defeat the New York Yankees in the series. After the ALCS, the Red Sox swept the Cardinals to win their first World Series since 1918 (86 years).