NEW YORK, NY - SEPTEMBER 01: Petra Kvitova of the Czech Republic serves during her first round match against Laura Siegemund of Germany on Day Two of the 2015 US Open at the USTA Billie Jean King National Tennis Center on September 1, 2015 in the Flushing neighborhood of the Queens borough of New York City. (Photo by Clive Brunskill/Getty Images)
