The first day of the US Open went as expected. Serena Williams extended her winning streak over Maria Sharapova. Novak Djokovic won his opener in straight sets. And Roger Federer was challenged early, but came away with a convincing victory.
But that doesn't mean the day was without excitement. Here are five weird and wonderful moments that went under the radar on Day 1:
"I am the BEST"
The past three seasons have been glorious for fans of Federer, Djokovic and Rafael Nadal. The three have won every single Grand Slam, and they've pushed one another to mind-boggling career-major tallies. US Open patrons are renowned for their passion, but this group in masks took it to a creepy level: