Kostyuk M. defeated Stephens S. 6-1, 7-5 at the US Open. She took control on return in the first set and protected her advantage with clutch serving in the second. Kostyuk won 25 of 31 first-serve points and saved three of four break points.
Kostyuk broke at 2-0 in the opening set, added another break at 5-1, and closed out the opener 6-1. Stephens improved in the second set, pulling level with a break at 4-4 after Kostyuk had moved ahead at 3-2. Kostyuk answered with a break at 6-5 to take the set 7-5.
The standout edge was Kostyuk's serving numbers: seven aces to Stephens' zero, and an 81 percent win rate on first-serve points. She converted three of eight break chances and saved three of four she faced, while Stephens landed a much higher first-serve percentage but could not make it count.