Doi ousted fourth-seeded Hsieh 6-4, 4-6, 7-6 (7-3). Doi won three more points (119-116) than Hsieh in the match, fewer than the four point-difference by which she won the tiebreaker.
Tatishvili took out fifth-seeded Monica Niculescu 4-6, 6-3, 6-2 with six breaks over the last two sets. She dropped just three points on serve in the decisive third set.
No. 3-seeded Alize Cornet stopped Magda Linette 6-3, 6-4 and seventh-seeded Chanelle Scheepers was a 2-6, 6-3, 6-4 winner over Shelby Rogers. Cornet and Scheepers are the only seeded players to advance out of the second round and they will play each other in the next round.
Also Wednesday, Eugenia Bouchard defeated Camila Giorgi 6-3, 6-0; Flavia Pennetta got by Maria-Teresa Torro-Flor 6-2, 6-3, Lucie Hradecka rolled past Lauren Davis 6-2, 6-2; and Johanna Larson advanced over Virginie Razzano 6-3, 6-3.