Naomi Osaka, of Japan, serves to Marta Kostyuk, of the Ukraine, during the third round of the US Open tennis championships, Friday, Sept. 4, 2020, in New York.
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.
Kerbers next opponent is another American, 28th-seeded Jennifer Brady, a 6-3, 6-3 winner against Caroline Garcia.
The key moment: Kostyuk held five break points that could have given her a 3-1 lead in the final set.
Each time on court during the tournament, Osaka is wearing a different mask in memory of a victim of racial injustice.