No one -- on Earth -- was more fired up about the Chiefs' epic comeback against the Houston Texans than Patrick Mahomes' girlfriend, Brittany Mathews ... and it's all on video.
Brittany WENT FULL ON BERSERK while watching her boyfriend engineer one of the greatest comebacks in NFL playoff history ... screaming, yelling, talking trash!!!
The 23-year-old was watching the game from a VIP suite at Arrowhead Stadium in Kansas City ... surrounded by other Chiefs players' GFs and her BFF Jackson Mahomes, Pat's younger bro.
As the Chiefs started cutting into the Texans 24-0 lead, Matthews could barely believe it -- LOSING HER MIND while Patrick went off on the field.