Roddick, seeded fifth, moved on when Jose Acasuso had to retire with a leg injury prior to the start of the fourth set. Roddick had a 4-6, 6-1, 6-2, lead when Acasuso said he could not continue.
Joining Roddick in the third round was Nikolay Davydenko, a 6-2, 6-2, 6-2, winner over Nicolas Kiefer.
Ninth-seeded Czech Tomas Berdych coasted past Simone Bolelli, 7-5, 6-3, 6-3, while the day's biggest upset came when Hyung-Taik Lee defeated 14th-seeded Guillermo Canas, 7-5, 7-5, 6-3.
Sharapova, the defending champion, needed only 51 minutes to defeat Casey Dellacqua, 6-1, 6-0. Next up for Sharapova will be Agnieszka Radwanska, who recorded a 6-2, 6-3, triumph over Virginie Razzano.