Carlos Alcaraz celebrated his US Open win on Sunday in epic fashion ... first, he doused himself in champagne -- and then he hit a New York hot spot and partied with models!!
The 22-year-old Spaniard beat Jannik Sinner 6-2, 3-6, 6-1, 6-4 at Arthur Ashe Stadium as President Donald Trump watched from the stands ... and before he left the venue, he popped some serious bubbly with his team.
Check out footage from his locker room celly -- Alcaraz surprised his pals with a massive container of booze, but they were armed with their own bottles .