Madison Keys completes American sweep in U.S. Open quarterfinals

Madison Keys of the United States celebrates defeating Kaia Kanepi of Estonia after their Women's Singles Quarterfinal match on Day Ten of the 2017 US Open at the USTA Billie Jean King National Tennis Center on September 6, 2017 in the Flushing neighborhood of the Queens borough of New York City.

Clive Brunskill / Getty Images

NEW YORK -- Madison Keys has made it an all-American women's final four at the U.S. Open. 

The No. 15 seed beat Kaia Kanepi 6-3, 6-3 to reach the semifinals of a Grand Slam tournament for the second time.

She will face No. 20 CoCo Vandeweghe on Thursday night in the second semifinal, after ninth-seeded Venus Williams faces unseeded Sloane Stephens. 

Venus Williams is vying for her third Grand Slam appearance this year, CBS Sports reports. She lost in the finals in both the Australian Open and Wimbledon to her sister Serena and new world No. 1 Garbine Muguruza, respectively. Stephens has won 13 of her past 15 matches, whereas Keys has won 11 of her last 12. It's an amazing run of tennis for American women, and it will all culminate in a Grand Slam win in New York. 

All of this is happening while Serena Williams is watching as a new mother, as she's been out since the Australian Open.  

The Americans hadn't had all four semifinalists at the U.S. Open since 1981, when Tracy Austin beat Martina Navratilova for the title. Chris Evert and Barbara Potter also made the semifinals.

The last time it happened at any Grand Slam tournament was at Wimbledon in 1985, with Navratilova and Evert joined by Zina Garrison and Kathy Rinaldi.

The U.S. Open is guaranteed its first all-American final since Serena Williams beat Venus in 2002.

In the men's bracket, no American men remain as Sam Querrey lost his quarterfinal match. 

Meanwhile, Juan Martin del Potro defeated Roger Federer, ending his 18-match Grand Slam winning streak.

Del Potro will meet up with Rafael Nadal in Friday's semifinals.