In the first round of the Australian Open, the first of the four Grand Slam tennis events of the year, the youngest player of the competition, beat world No. 27 and tournament 25th seed Shuai Peng of China 6-2, 6-2 in just 57 minutes, Ukrinform reports.
This is the first victory for 15-year-old Kostyuk in the Grand Slam qualifying and her first victory over a tennis player from the world's top 30.
Kostyuk's next opponent will be Australian Olivia Rogowska, who defeated her compatriot Jaimee Fourlis - 6-3, 6-7 (3-7), 6-2.
Last year, Kostyuk won the Australian Open junior girls title.