Karolina Pliskova cruised into the quarter-finals of the US Open with a straight-sets win over American Jennifer Brady.
The Czech world number one, 25, had to save match point before beating China's Shaui Zhang in the third round.
But she needed only 46 minutes to win 6-1 6-0 on Arthur Ashe Stadium against the world number 91, who was competing in the last 16 for the first time.
Pliskova will now face Coco Vandeweghe or Lucie Safarova in the next round.
However, she needs to reach the final at Flushing Meadows to have a chance at retaining her world number one ranking.