NEW YORK, NY - SEPTEMBER 08:  Karolina Pliskova of the Czech Republic celebrates defeating Serena Williams of the United States 6-2, 7-6 during their Women's Singles Semifinal Match on Day Eleven of the 2016 US Open at the USTA Billie Jean King National Tennis Center on September 8, 2016 in the Flushing neighborhood of the Queens borough of New York City.  (Photo by Al Bello/Getty Images)