Two-time Grand Slam winner Naomi Osaka battled into the last 16 of the US Open on Friday, requiring three sets to defeat 18-year-old Ukrainian Marta Kostyuk.

Osaka, the 2018 US Open champion, needed 2 hours and 33 minutes to beat the unseeded world No 137 6-3, 6-7 (4/7), 6-2 inside an empty Arthur Ashe Stadium.

“She was very good. I’m kind of scared of how she is going to be in the future,” Osaka said of her vanquished opponent.

Frustration got the better of the Japanese fourth seed in the second set. After recovering from 5-3 to force a tie-break she threw her racquet when Kostyuk tied the match 1-1.

But Osaka’s experience came through in the deciding set as she held her serve and broke Kostyuk twice to set up a match against 14th seed Anett Kontaveit of Estonia. Kontaveit progressed by beating Poland’s 24th seed Magda Linetter 6-3, 6-2.

Osaka, of Haitian and Japanese heritage, walked onto the court wearing a facemask emblazoned with the name of Ahmaud Arbery, an unarmed black man who was shot dead in broad daylight while jogging in the town of Brunswick, in southern Georgia, in February.

Osaka is wearing different masks honoring victims of racial injustice and police brutality throughout the tournament.

Germany’s 17th seed Angelique Kerber also progressed to the fourth round, making light work of American Ann Li 6-3, 6-4.

Kerber, the 2016 US Open, will go up against Jennifer Brady for a quarter-final spot after the American 28th seed knocked out France’s Caroline Garcia 6-3, 6-3.

Garcia had provided the biggest upset of the tournament on Wednesday when she eliminated top seed Karolina Pliskova.

Sixth seed Petra Kvitova of the Czech Republic advanced to the round of 16 at a Grand Slam event for the 20th time in her career. She beat 36-ranked American Jessica Pegula 6-4, 6-3. She will Shelby Rogers, who ousted Madison Brengle 6-2, 6-4 in an all-American affair.

In other games, eighth seed Petra Martic of Croatia swept aside unseeded Russian Varvara Gracheva 6-3, 6-3.

Martic will play Yulia Putintseva of Kazakhstan in the last 16 after the 23rd seed powered past Vera Lapko of Belarus 6-3, 6-3.

Results

3rd rd

Jennifer Brady (USA x28) bt Caroline Garcia (FRA) 6-3, 6-3

Angelique Kerber (GER x17) bt Ann Li (USA) 6-3, 6-4

Yulia Putintseva (KAZ x23) bt Aliaksandra Sasnovich (BLR) 3-6, 6-2, 6-1

Petra Martic (CRO x8) bt Varvara Gracheva (RUS) 6-3, 6-3

Naomi Osaka (JPN x4) bt Marta Kostyuk (UKR) 6-3, 6-7 (4/7), 6-2

Anett Kontaveit (EST x14) bt Magda Linette (POL x24) 6-3, 6-2

Shelby Rogers (USA) bt Madison Brengle (USA) 6-2, 6-4

2nd rd

Iga Swiatek (POL) bt Sachia Vickery (USA) 6-7 (5/7), 6-3, 6-4

Elise Mertens (BEL x16) bt Sara Sorribes (ESP) 6-3, 7-5

Caty McNally (USA) bt Ekaterina Alexandrova (RUS x21) 4-6, 6-3, 7-6 (7/2)

With AFP Inputs