As Major League Baseball’s Red Sox prepare to face the New York Yankees in an upcoming wild card postseason game, the longstanding Boston-New York sports rivalry played out unexpectedly on late-night television. On Monday’s episode of "Jimmy Kimmel Live!" a surprise attendee stirred the crowd when actor Matt Damon, a known Red Sox supporter and native of Cambridge, Massachusetts, made an unannounced appearance during the show’s first taping in New York City this week.

Damon’s presence injected a dose of playful tension into host Jimmy Kimmel’s usual monologue. Wearing a Red Sox cap, Damon loudly declared “Go Sox!” as the show referenced the upcoming matchup. The initial applause quickly gave way to boos once the camera zoomed in on the actor, setting the stage for a comedic exchange between the two longtime friends and on-air rivals.

Kimmel, who has engaged in a mock feud with Damon over several years, seized the moment to poke fun at the actor’s attempt to insert himself into the broadcast. “You, the loser in the Red Sox cap, what is your name?” Kimmel quipped. When Damon responded with his well-known name, Kimmel feigned ignorance, declaring, “I have no idea what your name is, and honestly, I don’t care because it’s time for the ceremonial throwing out of the first Red Sox fan. Please remove this Masshole from the theater.”

Damon explained he was not deliberately trying to be on the show and was merely attending the taping with family. When probed about the family members accompanying him, he jokingly introduced Kimmel’s own mother, Joan, and sister, Jill, revealing he was seated with them in the audience. This revelation led Kimmel to insist security escort Damon and the Kimmel family out of the theater, much to the amusement of the studio audience.

Before departing, Damon delivered one final rallying cry: “Let’s go Sox!” The lighthearted moment underscored both the playful dynamic between Damon and Kimmel and the enduring regional passion surrounding the upcoming Red Sox-Yankees game.