NEW YORK -- Naomi Osaka spiked her racket after one errant forehand late in the second set at the U.S. Open, then flung it the length of the baseline after a missed backhand return ceded that tiebreaker.
Sometimes, that's the sort of reaction it takes to right things for Osaka. And, perhaps surprisingly, she needed whatever push she could get in Friday's third-round match.
Facing an opponent competing in just her second major tournament, two-time Grand Slam champion Osaka eventually figured out a way to turn a tight one into a runaway and beat 18-year-old Marta Kostyuk 6-3, 6-7 (4), 6-2 by claiming the final five games at Flushing Meadows.
"While I was playing, honestly, I was cursing myself out," Osaka said during an on-court interview afterward, "so you wouldn't want to know what I was saying."
After taking things out on her racket, Osaka sat with a white towel draped over head during a changeover.
"It's what I do in times of extreme anger and frustration," she said.
Still, she improved to 7-0 since tennis resumed after a hiatus of more than five months because of the coronavirus pandemic.
With shadows creeping across the Arthur Ashe Stadium court in the early afternoon, the 137th-ranked Kostyuk certainly had her chances to pull off a significant surprise.
The key moment: Kostyuk held five break points that could have given her a 3-1 lead in the final set.
"A turning point," Osaka would say later.
She fended off every one of those and held to 2-all, beginning her match-closing run.
"I'm kind of scared how she's going to be in the future," said Osaka, who played with tape wrapping her left hamstring, which has been a problem since last week. "She has no fear."
Kostyuk had her own issues: She twice took a medical timeout to have a trainer tape her right ankle.
But she also was able to control the outcomes of points for stretches, winning 19 of the 23 points when she went to the net. The Ukrainian teen also delivered more winners than Osaka, 36-30, over the match's 2 1/2 hours.
"I guess I would say the thing that made me most displeased was probably the decisions that I was making and the fact that I started becoming way too passive," Osaka said, "and hoping that she would, you know, make an unforced error."
Before and after the match, Osaka wore a mask bearing the name of Ahmaud Arbery, a Black man who was fatally shot after being pursued by armed white men in Georgia.
Each time on court during the tournament, Osaka is wearing a different mask in memory of a victim of racial injustice.
"None of these deaths had to happen," Osaka said. "For me, I just want everyone to know the names more."
Another past U.S. Open champion moving into the fourth round Friday was 2016 titlist Angelique Kerber, who defeated 20-year-old American Ann Li 6-3, 6-4. Kerber's next opponent is another American, 28th-seeded Jennifer Brady, a 6-3, 6-3 winner against Caroline Garcia.
In the previous round, Garcia upset top-seeded Karolina Pliskova.
Sixth-seeded Petra Kvitova moved on with a 6-4, 6-3 win over American Jessica Pegula. Kvitova faces another American, Shelby Rogers, in the next round, trying to reach the quarterfinals of the U.S. Open for the third time.
Rogers, who is having her best run in the Grand Slam event, beat Madison Brengle 6-2, 6-4 earlier Friday.
No. 8-seeded Petra Martic advanced to the fourth round for the second straight year with a 6-3, 6-3 victory over .Varvara Gracheva.
Gracheva made too many mistakes, with 33 unforced errors -- three times as many as Martic.
As Gracheva's deficit grew larger and larger, she knew more than anyone that a comeback was still possible. In the previous round, she trailed No. 30 Kristina Mladenovic 6-1, 5-1 and faced four match points before coming all the way back to win.
There was no such turnaround this time.
Martic now will try to get to the second Grand Slam quarterfinal of her career after reaching that stage at last year's French Open.She has lost her other six fourth-round matches at major tournaments, including against Serena Williams at the US Open last year.
Martic will face off against No.23 Yulia Putintseva, who beat Aliaksandra Sasnovich 3-6, 6-2, 6-1, on Sunday.
Caty McNally, an 18-year-old from Ohio, eliminated No. 21 seed Ekaterina Alexandrova in three sets in a rain-delayed match to reach the third round.
McNally's 4-6, 6-3, 7-6 (2) victory gives the host country 11 women in the third round at Flushing Meadows for the first time since 1992.
The match was suspended Thursday because of the weather. McNally, who plays doubles with 16-year-old American Coco Gauff, had never been this far in singles at a Grand Slam tournament.
The Associated Press contributed to this report.