Sharapova continued her imperious march through the draw as she crushed US college player Mallory Burdette 6-1, 6-1 to reach the fourth round.
The Russian, who has lost just seven games in her first three matches, next plays compatriot Nadia Petrova, a 6-4, 7-5 winner over Czech Lucie Safarova.
Del Potro, the 2009 US Open winner, downed the US’ Ryan Harrison 6-2, 6-3, 2-6, 6-2, while 31-year-old wildcard Hewitt, who won the title in 2001, outlasted Gilles Muller of Luxembourg, 3-6, 7-6, 6-7, 7-5, 6-4 in four hours, 35 minutes.
In the women’s doubles, Taiwan’s Chuang Chia-jung and her playing partner Zhang Shuai of China defeated Eva Birnerova of the Czech Republic and Romina Oprandi of Switzerland 7-5, 7-5.
Another Taiwanese player going through to the third round is Hsieh Su-wei, who with her partner Anabel Medina Garrigues of Spain defeated Vera Dushevina of Russia and Tamarine Tanasugarn of Thailand 6-4, 6-4.
Additional reporting by Staff writer