Lleyton Hewitt labored and Maria Sharapova hardly broke a sweat but both advanced at the US Open Sunday afternoon. The top-seeded Sharapova is through to the quarterfinals after breezing past India's Sania Mirza 6-2, 6-1. Sharapova moves on to face ninth-seeded Nadia Petrova who defeated Nicole Vaidisova 7-6, 7-6. Hewitt was forced to a fifth set by American Taylor Dent, but won his third-round match 6-3, 3-6, 6-7, 6-2, 7-5. Dent had 19 aces compared to eight by Hewitt who also struggled with his serve committing eight double faults. The match lasted three hours and 21 minutes.Hewitt will play Dominik Hrbaty in the fourth round.