Serena the Swiftie! Williams attends Taylor Swift's Miami Eras Tour show

Taylor Swift might be a tennis fan now, but the Eras Tour is still the hottest ticket on tour. Just ask Serena Williams, one of the famous faces in the crowd at Hard Rock Stadium over the weekend for one of Swift's three shows in Miami.

Joining other celebs including Tom Brady and his two sons, Today hosts Hoda Kotb and Jenna Bush-Hager, and thousands of other fans who flocked to the home of the Miami Dolphins and the Miami Open, Williams dubbed herself "a casual Swiftie" as she posted a behind-the-scenes video of her getting ready to attend the show on her social media.

"Or maybe not so casual," she later teased as the video transitioned to a scene of the former world No. 1 jumping, dancing and singing along, all soundtracked to Swift's hit You Belong with Me.

The Eras Tour is set to conclude in Canada in December after more than 18 months of shows, more than $1 billion reportedly grossed, and even a movie produced, and Williams isn't the only tennis star to have attended. The tour's chief Swiftie, Iga Swiatek, attended a stop in June, and Roger Federer was in the crowd for July's Zurich show.

Read more: Wildest Dreams ... come true! Iga Swiatek finally sees Taylor Swift's Eras Tour

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And this weekend, Williams wasn't the only member of her own household to snag the coveted tickets either. Williams' husband, Alexis Ohanian, and 7-year-old daughter, Olympia, also attended, and got into the spirit by accessorizing with matching T-shirts.

Reddit co-founder Ohanian earned applause from netizens as he showed off an "I Love Taylor (my daughter made me wear this)" tee that the one she wore to what her father said was her first-ever concert.

"You did your daughter proud," one fan wrote on Instagram. "She will remember this forever."

"You're such a GREAT girl dad," wrote another.

The core memory will stick with him forever, Ohanian wrote on his recap post.

"I’m a Swiftie now. Amazing experience. Fantastic performance. Olympia’s first ever concert will be VERY hard to top," he said.