There will be a noticeable lack of star power ahead of the U.S. Open draw announcement on Aug. 25. On the women's side, six-time U.S. Open champion Serena Williams is shut down due to her pregnancy, while on the men's side, 2016 finalists Stan Wawrinka and Novak Djokovic are sidelined with injuries, which could potentially pave the way for surging Roger Federer and Rafael Nadal to capture another