When the clock struck 12 for Cinderella, she had to rush home before her carriage turned into a pumpkin. For Venus Williams, midnight had quite the opposite effect. In fact, it proved the perfect time for the first-time Met Gala co-chair to kick off her own after-party.

Sleek new Flatiron venue The Amber Room played backdrop for the late-night soirée. Starting at 11 p.m., guests began mingling and settling into green velvet booths beneath the soaring space’s painted tin ceiling. Some ordered bottle service while others picked up Champagne, espresso martinis, or vodka sodas from the bar. Williams arrived with husband, Andrea Preti, just before 12:30 a.m—which didn’t even count as late, as she appeared three minutes before her slated arrival time. By Met Gala after-party standards, call it fashionably early, if anything.

After making her rounds in a black Swarovski gown at the Met, Williams stayed-on theme for the remainder of the night. For the soirée, the tennis ace slipped into a custom-designed anOnlyChild black bubble dress with crystal-trimmed Jimmy Choo mules and a matching BonBon bag. However, she gave the look a nonchalant edge with a black leather jacket. Preti also swapped his classic tuxedo for an on-trend military-style jacket with golden epaulettes by Who Decides War.

If Williams’ attire wasn’t proof enough that it was time to party, one only had to look around the mirrored and pink velvet-paneled room, awash in the glow of backlit columns, rounded lights, and tortoiseshell counters. Most guests wore an array of bodycon, sequin, and cut-out dresses with slip-on mules and vintage handbags. Others took a more casual route with dark denim, printed blazers, Letterman jackets, and sneakers. That wasn’t true of Williams’ all-star sister Serena Williams, though, who arrived at 1:40 a.m. in a ruched gray dress and black blazer, complete with gleaming diamond tennis studs. Both sisters’ jewels caught the light as they danced together—Champagne flutes in hand—to a DJ set filled with tracks by Doechii, Rihanna, and Beyoncé.

The pair were joined in the VIP lounge by a selection of stylish friends, including Ty Dolla $ign, Leon Thomas, Jasmine Tookes, Bach Mai, Kate Barton, Ashley Moubayed, Tari Eason, and Ladies of London’s Emma Thynn.

None were fazed by the late night, especially as party hopping is the post-Gala norm. “You have to pace yourself. Start at a party where you know the most people, or you know it’ll be a good crowd—and then try to hit a few more nearby,” designer Kate Barton advised, “I would like to cap it at three. You never know where the night will take you—it’s still young.”

“My strategy is simultaneously being everywhere and nowhere at the same time,” said Moubayed, the designer behind Don’t Let Disco, who had popped up at this weekend’s Vogue Café. “For any party, I always pick something that makes me really feel me, and really sexy. It has to be comfortable—although it’s okay if it’s 30% to 50% not comfortable.”

Despite unfound whispers that 50 Cent or Busta Rhymes would perform at the bash, attendees remained in high spirits—and the lounge was still bustling well past 3 a.m. Both Williams sisters left shortly beforehand—moments after Venus changed shoes one last time before exiting, signing off in a pair of slingback kitten heels. Cinderella would approve!