* Wozniacki to play Errani in quarters * Cilic advances to fourth round against Simon * Federer match suspended due to lightning, rain (Adds details, quotes) By Larry Fine NEW YORK, Aug 31 (Reuters) – Caroline Wozniacki upset French Open champion Maria Sharapova in a groundstroke marathon to reach the U.S. Open quarter-finals, while Gilles Simon registered the first big surprise in the men’s draw on Sunday. France’s Simon, the 26th seed, defeated Spanish fourth seed David Ferrer, who became the first top 10 men’s seed to be shown the exit when he fell 6-3 3-6 6-1 6-3 in the third round on a hot, humid day at Flushing Meadows. The 10th-seeded Wozniacki, who ruled as world number one for 67 weeks but never won a grand slam crown, showed great grit in battling to a 6-4 2-6 6-2 victory over fifth seed Sharapova in a two hour 37 minute slugfest in sweltering conditions.