成人快手

She's 15 years old and playing at the Australian Open; her first Grand Slam tennis tournament. And the teenager from Ukraine has become the youngest player to reach the third round of a Grand Slam in 20 years. She's been playing since she was four, but hasn't always liked the sport. We asked our commentator in Melbourne, Gigi Salmon, to tell us more about her.

(Photo: Marta Kostyuk celebrates winning a point in her Junior Girls Singles Final match during the Australian Open 2017 Junior Championships, Credit: Jack Thomas/Getty Images)