We break down the numbers, sift through the history, and make our predictions below.
Pliskova also played the first match on Ashe on Saturday. The Czech will have to reach the final to guarantee that she stays atop the rankings. On the face of things, Keys seems to have the easier path to the semifinals.
2 - Number of Spanish men (Rafael Nadal, Pablo Carreno Busta) in the semifinals, the first time that's happened at the U.S. Open. I was never actually defending a final of a grand slam. I think it will be an easier match to the tune of 6-2 6-4.
She just went on record challenging the great Kobe Bryant to a tennis match. With the loss, Wimbledon victor Garbine Muguruza takes the No. 1 ranking on Monday.
Karolina Pliskova must now make the final to keep the world number one ranking from Spaniard Garbine Muguruza, and the Czech cruised into the quarter-finals.
Venus Williams, 37, has also advanced, overcoming two-time Wimbledon champion Petra Kvitova in a thrilling three-set contest. Not since 2002, when Serena Williams, Lindsay Davenport, Jennifer Capriati, Monica Seles and Venus Williams all won in the round of 16, have so many American women reached the quarterfinals.
In doing so, Keys became the fourth American to win entry into the U.S. Open women's quarterfinals.
Having the home advantage, Keys came into the match knowing that she could be the fourth American to enter the quarterfinals with a win here.
In 1981, Tracy Austin cruised past Barbara Potter in the semifinals, then outlasted Martina Navratilova for the title.
Tiebreakers have been the key to success for this generation of Americans as well. That match will follow No. 9 Venus Williams vs. unseeded Sloane Stephens.
Pliskova was the runner-up to Angelique Kerber at Flushing Meadows past year and needs to get back to the final in order to remain atop the WTA rankings.
We really want to see Kobe take her up on this.
Her mother, Tauna Vandeweghe, was a swimmer in the 1976 Olympics. (Physically, perhaps, as well.) Some of that can surely be attributed to her new coach, former Wimbledon champion Pat Cash.
But there is no quibbling with Vandeweghe's results in the Grand Slam tournaments. She's now in her second career grand-slam semifinal, the other coming at the 2015 Australian Open.
Yesh: Pliskova has struggled at times, but when she is on so few players can beat her. Vandeweghe can match her for power, but Pliskova is much more consistent at the end of the day. "It's a process", she said, "but I couldn't wish for anything better".