The cheers started on the first hole for McIlroy, and for the next four hours they didn't stop. To frequent deafening chants of "let's go Rory," the Northern Ireland native capped a record-setting performance by finishing 16 under par.
That's the best score ever at a U.S. Open, and prior to Friday, no one at any point had been better than 12-under during the tournament's 111-year history.
He won by eight shots, and after Friday, it seemed there were no other golfers that could come close to the 22-year-old. Y.E. Yang of South Korea did, but only because he was McIlroy's playing partner for the final two rounds.
"I think he's still growing. And it's just scary to think about it," says Yang.
Jason Day of Australia finished second.
"It's just phenomenal golf. He lapped the field," Day said. "And for such a young age and how mature he is, golf is in a really, really good spot because of where Rory is right now."
The enthusiastic crowd would agree.