Frances Tiafoe and Andreas Seppi go back and forth in a rally that ultimately ends with a Tiafoe backhand winner. (1:03)

MELBOURNE, Australia -- The Australian Open kicked off Monday with ample storylines to satisfy American tennis fans: Serena Williams' first Melbourne run since returning from maternity leave, Venus Williams' first major without longtime coach David Witt, Sloane Stephens, Madison Keys ... you get the point.

But it's teen sensation Amanda Anisimova, 17, and 20-year-old Frances Tiafoe who've stolen the show Down Under. The dynamic duo is all the talk around Melbourne Park, and if their rising Twitter followers are any indication, the buzz is global.

Tiafoe has been electric on court, but it's his unique-to-tennis postmatch celebrations that are trending. After his second-round upset of No. 5 Kevin Anderson -- the biggest win of the young American's career -- he channeled his inner LeBron:

After his Australian Open 2nd round upset victory over (5) Kevin Anderson, Frances Tiafoe won again last night, defeating Andreas Seppi in the 3rd round. pic.twitter.com/KMeVQZOQU5 — The Undefeated (@TheUndefeated) January 18, 2019

Tiafoe saved his best LeBron James impression for a five-set win over Andreas Seppi in the third round, and then had this to say: "Guys are loving it. It'll be interesting to see if guys want to try them. Just trying to bring something in tennis. I'm a big basketball fan. Love the team celebrations. If I get a chance to do it on a big court, big situation, you got to bring it up. It's not pre-med. I don't know what celebration I'm going to do. I got a lot of them."

We can't wait to see what he brings if he pulls off a fourth-round win over Grigor Dimitrov -- on Tiafoe's 21st birthday. We suspect it might be pre-med.

Frances Tiafoe does the Lebron James Celebration after beating Andreas Seppi in the Third Round of the 2019 Australian Open. Side-by-side comparison. @KingJames @FTiafoe @AustralianOpen @NBA #AusOpen pic.twitter.com/KbhGjJrqW3 — bryzonstudios (@bryzonstudios) January 18, 2019

For her part, Anisimova's celebrations are slightly more reserved:

A star in the making! American Amanda Anisimova stuns Sabalenka 63 62 to move on at the #AusOpen pic.twitter.com/mW8RltZTR1 — SI Tennis (@SI_Tennis) January 18, 2019

She saves her thrills for the court. This shot in the second set of her straight-sets win over No. 11 Aryna Sabalenka is being called the point of the tournament. Heck, shot of the year?

The first player born this century (Aug. 31, 2001) to reach the fourth round at a Slam, Anisimova is the youngest player remaining in the draw, the youngest American to reach the fourth round at a major since Serena at Roland Garros in '98 and the youngest in Melbourne since Jennifer Capriati in '93. On court, and with reporters, she is mature beyond her years. Thankfully, Twitter exists to remind us she's still 17.

I thought I woke up with three new freckles around my hands, but they're just sharpie marks 🤣 I love you guys — Amanda Anisimova (@AnisimovaAmanda) January 16, 2019

If that wasn't reminder enough, there's this: Born in Freehold, New Jersey, Anisimova balked when asked by the New York Times about a certain rock star with whom she shares a hometown. "Wait -- Bruce who? Is he, like, old?" Kids these days.