The Kansas City Chiefs pulled off an all-time regular-season upset in Foxborough, Massachusetts, on Sunday, with last year's MVP Patrick Mahomes leading the AFC West club over the vaunted New England Patriots, 23-16.

During the game, however, security concerns reportedly affected how Mahomes' girlfriend, Brittany Matthews, could enjoy the Chiefs victory.

Per Matthews' Twitter, via Bleacher Report, the woman dating the reigning NFL MVP was harassed and taunted by Patriots fans in the stands.

“This place is horrible, people already yelling every time I stand up, am I not aloud [sic] to stand up for [a] football game?

“As soon as we sit down, drunk dude [says] ‘hey everyone this is Patrick Mahomes' girl and brother, let's give them s**t.' This shall be fun.”

Eventually security at Gillette Stadium, the Patriots' home field, had to intervene, rescuing Mahomes' guests from fans' jeers.

“Gillette security came and got us and moved us to a safe space,” Matthews tweeted yesterday. “That's how you know it was bad.”

Matthews and Mahomes' brother witnessed the 24-year-old gunslinger throw 26/40 for 283 yards, a touchdown, and one interception in the rare road win for a young signal-caller up against Tom Brady and the intimidating New England team in enemy territory.

The “enemy” made itself quite clear when Matthews' identity was revealed and exploited by some Patriots fans. New Englanders also reportedly booed their own team—the reigning Super Bowl champions who are 10-3 this season—when they left the field at halftime.

Despite the heckling, Matthews had the opportunity to witness her beau clinch an AFC West title for Kansas City in Sunday's win.