Next month, Arthur Ashe Stadium will be teeming with Lacoste polo shirts and tasteful chinos. Tennis fans will order $69 caviar plates (one ounce of hackleback) and $17 signature cocktails (vodka, lemonade, raspberry liqueur and honeydew melon balls) at Lure Oyster Bar. The fortunate few will watch players like Federer, Williams and Nadal from suites paid for by credit card companies and white-shoe law firms.

That is all in the future, though. This weekend, Arthur Ashe Stadium was teeming with, well, teenagers. There were also preteens (with their attendant parents) and men in their 20s, and occasionally 30s.

But there were a lot of teenagers. They made their way to the U.S.T.A. Billie Jean King National Tennis Center in Queens to watch their favorite competitors play their favorite game: Fortnite.

Kyle Giersdorf, 16, known as Bugha, won the first prize of $3 million. “Everything I’ve done, the grind, it’s all paid off,” he said. “It’s insane.”