A marquee US Open fourth-round match up ended with an upset victory, as Caroline Wozniacki advanced to the quarterfinals of a Grand Slam for the first time in over two years. She outlasted Maria Sharapova 6-4, 2-6, 6-2 in a match that took over two and a half hours. Wozniacki had better fitness on the day and was eager to play each and every next point. Sharapova's loss means that the only top-six woman remaining is Serena Williams.
Wozniacki was able to break on Sharapova's first service game on the way to taking the first set. Sharapova had 21 unforced errors in that set and only won three of nine second serve points. Wozniacki's seven unforced errors showed a consistent game plan that relied on the opponent to make a mistake.
Sharapova took the second set thanks to winning over 80% of her first serve points. As the match progressed Sharapova seemed to take more time between points. Those familiar with her game know that she likes to go well behind the baseline after every point and regain focus. It often borders on time wasting, but is rarely ever something the chair umpire warns Sharapova from doing.
In this case, Sharapova was given a warning for taking too long to come back between the second and third sets. As the third set progressed Wozniacki continued to highlight how long Sharapova took between points. It was clear Sharapova was trying to conserve her energy. Wozniacki, who is also training for a marathon, never lost her fitness and was ready to go. She remained consistent and Sharapova uncharacteristically had trouble winning her first serve points in the final set.
Wozniacki will face Sara Errani in the quarterfinals after she beat Mirjana Lucic-Baroni in three sets.