Red Sox–Yankees rivalry

The Red Sox–Yankees rivalry is a Major League Baseball (MLB) rivalry between the Boston Red Sox and the New York Yankees. Both teams have competed in MLB's American League (AL) for over 120 seasons, and have developed what is considered by many to be the fiercest rivalry in American sports. Coined "The Rivalry" by some, the 1919 sale of star Red Sox player Babe Ruth to the Yankees popularized one of the most well-known aspects of the rivalry: a superstition known as the "Curse of the Bambino", attributed to Boston’s 86-year World Series drought which began upon Ruth’s sale to New York. Much like the Mets–Yankees rivalry, the Yankees have often been portrayed as the dominant heel, whereas the Red Sox have garnered a long-standing reputation for being an unfavored underdog. The Red Sox' case for being an underdog in the rivalry was made most notably during media coverage of the 2004 American League Championship Series (ALCS), where Boston overcame a 3–0 deficit in the series to win the American League pennant; the Red Sox would then go on to win the 2004 World Series.

The rivalry is often a heated subject of conversation, especially in the home region of both teams, the Northeastern United States. Until 2014, every MLB postseason featured one or both teams beginning with the inception of the wild card format and resultant additional Division Series in 1995, when both teams were assigned to the American League’s East Division. The Red Sox and the Yankees have faced each other three times in the ALCS, with the Yankees winning twice, in 1999 and 2003, and the Red Sox winning in 2004. The two teams have also met once in the American League Division Series (ALDS), in 2018, with Boston winning 3–1, a series which included a 16–1 Red Sox win in Game 3 at Yankee Stadium, the largest margin of defeat in a postseason game in the Yankees' history. The Red Sox also beat the Yankees in the 2021 American League Wild Card Game.

In addition, the teams have twice met in the last regular-season series to decide the AL pennant, in 1904 (when the Red Sox, then known as the Americans, won) and 1949 (when the Yankees won).

The Yankees and the Red Sox finished tied for first in 1978; subsequently, the Yankees won a high-profile tie-breaker game for the division title. The first-place tie came after the Red Sox had a 14-game lead over the Yankees more than halfway through the season. Similarly, in the 2004 ALCS, the Yankees ultimately lost a best-of-seven series after leading 3–0. The Red Sox comeback was the only time in American baseball history that a team has come back from a 3–0 deficit to win a series. The Red Sox went on to win the World Series, ending the 86-year-old curse.

This match-up is regarded by some sports journalists as the greatest rivalry in sports. Games between the two teams often generate considerable interest and receive extensive media coverage, including being broadcast on national television. National carriers of Major League Baseball coverage, including Fox/FS1, ESPN, and MLB Network carry most of the games in the rivalry across the nation, regardless of team standings or playoff implications. Yankees–Red Sox games are some of the most-watched MLB games each season. Outside of baseball, the rivalry has led to violence between fans, along with attention from politicians and other athletes.