Oudin and Zheng were among six players who finished matches before rains hit Thursday. One third-round match was still to be completed.
Oudin rolled over Elena Vesnina 6-0, 6-2 in a brisk 61 minutes. Oudin had five breaks in seven receiving games. She took control of the match in the first set, allowing Vesnina just seven points -- two on serve.
Zheng defeated Andrea Hlavackova 6-4, 6-1. Hlavackova had 11 break-point opportunities but Zheng fought them all off while converting three of her 10 break chances.
Fourth-seeded Roberta Vinci outlasted local favorite Heather Watson 6-3, 4-6, 6-1, winning 75 percent of the points in the third set. No. 5-seeded Jelena Jankovic moved into the quarterfinals via a walkover as Casey Dellacqua withdrew because of illness.
No. 8-seeded Ekaterina Makarova got past ninth-seeded Marina Erakovic 2-6, 6-1, 6-3 with five breaks, while 13th-seeded Hsieh Su-Wei routed Melinda Czink 6-1, 6-2 and Irina Falconi beat Urszula Radwanska 7-5, 6-3.