The USMNT's soccer game against Mexico turned VERY ugly Sunday night ... 'cause fans in the stands yelled anti-gay slurs and also violently threw objects at players.
The disturbing scenes all went down late in the CONCACAF Nations League final in Denver ... when the game actually had to be paused over homophobic chants.
Fans in the stands could reportedly be heard screaming a Spanish word that translates into an anti-gay insult -- and the chanting grew so loud, refs had to halt play until it stopped.
But, the unruly behavior didn't end there ... 'cause throughout the end of the wild soccer match, players were hit by debris thrown from the stands.