Madison Keys and Coco Vandeweghe completed the clean sweep for American women players on Wednesday, giving the host country all four U.S. Open semifinal spots for the first time since 1981.
Keys, seeded 15th in the event, was never really troubled by Kaia Kanepi of Estonia in the quarterfinals, claiming a 6-3, 6-3 victory in just 69 minutes. In an earlier match, 20th-seeded CoCo Vandeweghe triumphed at 7-6(4), 6-3 against 2016 runner-up and top-seeded Karolina Pliskova of the Czech Republic.
American veteran Venus Williams and Sloane Stephens have already set up an all-American semifinal in the bottom half in the previous day. Keys and Vandeweghe will face each other in the other semifinal.
"It feels so good. We have so many Americans to talk about in the last days of the U.S. Open, I can't tell you how many times I have sat in this chair and had to hear how horrible tennis is in America," said Keys.
"This means the world to me," said Keys, also a semifinalist at the 2015 Australian Open. "If someone told me this is where I would be right before Wimbledon, I wouldn't have believed you."
Vandeweghe's victory also means that Pliskova will hand the number one spot to Wimbledon champion Garbine Muguruza after staying just eight weeks on the top of the rankings.
"I won the juniors here when I was 16 and dreamed of playing on the real stage," said 25-year-old Vandeweghe.
Pliskova, who had to save a match point to beat China's Zhang Shuai in the second round, needed to fight back from breaks down in both sets to keep her challenge alive.
But Vandeweghe can pull away with her powerful groundstrokes every time the Czech posed a threat. Vandeweghe hit 24 winners compared to just 15 from Pliskova. The American also powered five aces on the way to her impressive victory.