The 22-year-old ended Svitolina's dreams of becoming the world number one after fighting from 4-2 down to clinch the decider. The Argentine Juan Martin del Potro, the champion in 2009 at Flushing Meadows, has, meanwhile, saved two match points and erased a late two innings to beat Austrian Dominic Thiem 1-6, 2-6, 6-1, 7-6 (1), 6-4. "My first good match, actually", Pliskova said.
Vandeweghe's win highlights what has been an incredible run for American women in the U.S. Open thus far. But del Potro won their meeting in the 2009 final in NY in five sets for his only Grand Slam title, ending Federer's streak of five straight U.S. Open championships - and he hasn't won the trophy since. They work just as hard as I do.
To get to the quarterfinals, Pliskova won 92 percent of her first serves and recorded 23 winners against Brady. Despite not winning too many tournaments or not even some big ones, she went on reaching the highest stages at nearly every WTA event she went for.More news: Fed Vice Chairman Fischer to resign for 'personal reasons'
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With the roof again closed over Arthur Ashe Stadium because of rain, the noisy support of the crowd drove Vandeweghe forward, in the same way that the fans had helped to inspire Williams and Stephens to their respective victories over Petra Kvitova and Anastasija Sevastova.
Two breaks apiece ensured the opening set went to a tie-break, and it was the American who took it 7-2 after Svitolina dropped serve three times.
Pliskova, who had been a match point down in her previous match, destroyed Jennifer Brady 6-1 6-0 in just 46 minutes to move into the US Open quarter finals. She netted a forehand on her first opportunity to clinch the match but on the second a service victor completed her victory to a roar of approval from the crowd. "You experience it at Wimbledon, but also experiencing it here for the first time with the roof closed was really exciting". We have to admire Serena, Venus, Lindsay [Davenport] and Jennifer [Capriati]. "Maybe I'm going to feel better in the next Grand Slams". But she left five more break points on the table, and for a player with highly praised strokes, she only hit 13 winners off the ground. "Let's make it four for four".
Pliskova, 25, needed to reach the final to hang on to the number one ranking, but defeat means she will be replaced by Spain's Garbine Muguruza in the new standings next week.