Roger Federer caused insane pandemonium out in the Big Apple on Tuesday ... when a crush of passionate fans crowded together to try to get a brief glimpse of the tennis superstar.
TMZ Sports got video of the insane scene outside Uniqlo on Fifth Avenue in NYC ... where Federer was doing a Q&A for the clothing brand.
Of course ... Federer -- currently the #3 ranked male tennis player -- famously left Nike for the Japanese company last year for $300 MILLION.
Just by looking at the scene outside the store, it's clear 38-year-old Federer is still one of the biggest sports superstars on the planet.