Pliskova needed to dig deep against Nicole Gibbs in the second round and had to save a match point against Zhang Shuai last time out, but she was rarely troubled by Brady, cruising to a 6-1 6-0 triumph on Arthur Ashe Stadium.
Against an undoubtedly tricky opponent capable of playing well above her unseeded status, this was an impressive performance from Vandeweghe, who successfully backed up her win over Agnieszka Radwanska with 16 winners and six aces today. The Czech Republic native is in the quarters for the second consecutive year. I think she was just much better in that match and Garbine was not her best.
It was Safarova who got off to the best start in the tiebreak, securing a mini-break in the opening point, though quickly lost it as Vandeweghe began to sense victory.
It was a different matter in the morning NY sunshine on Monday as qualifier Brady was left utterly demoralised by the class, movement and shot selection of the Czech player, who must reach the final to hang on to her position as the game's top seed.
Brandon: Pliskova is one of three women still in the race for the world #1 ranking after the completion of the US Open. "If there's some all-American matchups in the rest of the tournament, I think that says really good things about women's tennis".
Pliskova felt that she played one of her best matches of the year.
"We both have the plan to play aggressive, but I think she's a little bit, not messy sometimes, but she's just going for her shots".
Nadal also hit form at the US Open to stroll into the quarters for the first time in four years.
Yesh: Kanepi has had the most under-the-radar dream run at a Slam that I can remember. "My energy dropped. Once I got broken in the third, I just kept telling myself: 'Just try to figure it out".
Keys next will face the surprise of the tournament, 32-year-old Kaia Kanepi of Estonia, who advanced to the quarterfinals with a 6-4, 6-4 victory over 20-year-old Daria Kasatkina of Russian Federation. "Next time I play on it, I'll know what to expect", said Brady. I was lucky that I had an unbelievable crowd and atmosphere.
And Keys joins Sloane Stephens, Venus Williams and Vandeweghe in the quarterfinals.
While Muguruza won't accumulate further points as she was ousted by Petra Kvitova in yesterday's session, the young Ukrainian Svitolina is still a threat, and she may face Pliskova in the semis. Even if she just miss like 5 meters out, she doesn't care, so it's different.