Melbourne - Unseeded Naomi Osaka downed local Australian Open hope Ashleigh Barty with a comprehensive 6-4, 6-2 win Saturday to reach the last 16 of a Grand Slam for the first time.
Ranked 72, her reward is a clash with top seed Simona Halep for a place in the quarter-finals.
The powerful Japanese 20-year-old took the first set against the 18th seed in 38 minutes before racing to a 4-0 lead in the second on the back of an impressive serve.
Barty finally got on the board in her third service game but it was too little too late to the dismay of the raucous band of "Ash's Army" supporters on Margaret Court Arena.
Osaka, who beat this year's fourth seed Elina Svitolina in Melbourne as an 18-year-old two years ago, served out calmly -- smacking down her 12th ace on match point to win in 73 minutes.
"I feel really happy, but also I'm sorry because I know you all really wanted her to win," Osaka, whose mother is Japanese and father is Haitian, told the crowd afer her win to great applause.
"I'm honoured to be playing for Japan," she said before adding that she had benefited from a late switch of the match from the Rod Laver Arena centre court to the smaller venue because of matches overrunning.
"I think there would have been a lot more people cheering for her there so it was good for me," she said. "Thank you all for a great atmosphere. I always wanted to experience playing against an Australian here."
Results from the Australian Open on Saturday:
Dominic Thiem (AUT x5) bt Adrian Mannarino (FRA x26) 6-4, 6-2, 7-5
Tennys Sandgren (USA) bt Maximilian Marterer (GER) 5-7, 6-3, 7-5, 7-6 (7/5)
Marton Fucsovics (HUN) bt Nicolas Kicker (ARG) 6-3, 6-3, 6-2
Fabio Fognini (ITA x25) bt Julien Benneteau (FRA) 3-6, 6-2, 6-1, 4-6, 6-3
Chung Hyeon (KOR) bt Alexander Zverev (GER x4) 5-7, 7-6 (7/3), 2-6, 6-3, 6-0
Karolina Pliskova (CZE x6) bt Lucie Safarova (CZE x29) 7-6 (8/6), 7-5
Madison Keys (USA x17) bt Ana Bogdan (ROM) 6-3, 6-4
Simona Halep (ROM x1) bt Lauren Davis (USA) 4-6, 6-4, 15-13
Caroline Garcia (FRA x8) bt Aliaksandra Sasnovich (BLR) 6-3, 5-7, 6-2
Naomi Osaka (JPN) bt Ashleigh Barty (AUS x18) 6-4, 6-2
Barbora Strycova (CZE x20) bt Bernarda Pera (USA) 6-2, 6-2