Managed by Terry Francona, the Red Sox finished with a 98–64 record, three games behind the New York Yankees in the American League East.

The Red Sox qualified for the postseason as the AL wild card, swept the Anaheim Angels in the ALDS, and faced the Yankees in the ALCS for the second straight year.

[33] During the 2003–04 off season, the Red Sox acquired a starting ace pitcher; Curt Schilling, as well as a closer, Keith Foulke.

A bright point came on July 24, when the Red Sox overcame a five-run deficit as Bill Mueller hit a game-winning home run to right-center off Yankees closer Mariano Rivera.

The game also featured a now infamous brawl between Yankee superstar Alex Rodriguez and Red Sox catcher and captain Jason Varitek.

[119][120][121] Red Sox General Manager Theo Epstein shook up the team at the MLB trading deadline July 31, trading the team's wildly popular yet often hurt and disgruntled shortstop, Nomar Garciaparra, to the Chicago Cubs,[122] receiving Orlando Cabrera from the Montreal Expos and Doug Mientkiewicz from the Minnesota Twins in return.

In a separate transaction, the Red Sox also traded AAA outfielder Henri Stanley to the Los Angeles Dodgers for center fielder Dave Roberts.

However, the Sox' 2003 off season prize pickup Curt Schilling suffered a torn tendon when he was hit by a line drive.

In game three, what looked to be a blowout turned out to be a nail-biter, as Vladimir Guerrero hit a grand slam off Mike Timlin in the top of the seventh inning to tie it at six.

However, David Ortiz, who was noted for his clutch hitting, delivered in the 10th inning with a game winning two-run homer, off Jarrod Washburn, sailing over the Green Monster.

The Red Sox advanced to a rematch in the 2004 American League Championship Series against their bitter rivals, the New York Yankees.

Curt Schilling pitched with the torn tendon sheath in his right ankle he had suffered in Game 1 of the Division Series against Anaheim, and was routed for six runs in three innings.

Yankee starter Mike Mussina retired the first nineteen Red Sox that came to the plate before Mark Bellhorn broke it up with a double with one out in the top of the seventh.

At that point in the history of baseball, no team had come back to win from a 3–0 series deficit (only the 1998 Atlanta Braves and 1999 New York Mets had ever gotten as far as a Game 6).

In Game 4, the Red Sox found themselves facing elimination, trailing 4–3 in the ninth with Yankees closer Mariano Rivera on the mound.

After Rivera issued a walk to Kevin Millar, Dave Roberts came on to pinch run and promptly stole second base, this being what many consider the turning point in the series.

With the series returning to Yankee Stadium for Game 6, the improbable comeback continued, with Curt Schilling pitching on an ankle that had three sutures wrapped in a bloody white sock (red with a blood stain).

Originally called a double, the umpires conferred and agreed that the ball had actually gone into the stands before falling back into the field of play.

A key play came in the bottom of the eighth inning with Derek Jeter on first and Alex Rodríguez facing Bronson Arroyo.

With no outs, Suppan should have scored easily from third on a Larry Walker ground ball to second baseman Bellhorn, who was playing back, conceding the run.

Many Red Sox fans who were turned away due to no tickets for the game were allowed to watch the final inning from the confines of Busch Stadium after being let in free of charge.

"The Red Sox held a parade (or as Boston mayor Thomas Menino put it, a "rolling rally") on Saturday, October 30, 2004.

A crowd of more than three million people filled the streets of Boston to cheer as the team rode on the city's famous Duck Boats.