Sunday at the 2016 US Open was not a good day for two of the WTA's biggest hitters as both Petra Kvitova and Madison Keys failed to advance into the quarter-finals.
While two-time Wimbledon champion Kvitova fell to Angelique Kerber on her quest to clinch the #1 ranking, Madison Keys suffered a frustrating loss against Caroline Wozniacki, ending the young American's promising run prematurely.
