(CNN) -- Ana Ivanovic was ousted from the Australian Open in the second round by Argentina's Gisela Dulko, losing in a three-set thriller.
Ivanovic, the No. 20 seed at the year's first Grand Slam in Melbourne, won the first set that ended in a tiebreak 7-6 (8-6), but lost the last two sets, 5-7, 4-6.
"There are still some areas that are not there for me to rely on when ... I need them the most. Some matches it's there, some not. I just have to sort of keep my head up and try to improve," she told australianopen.com.
In other women's play on Thursday, No. 4 seed Caroline Wozniacki easily dispatched of Germany's Julia Goerges 6-3, 6-1, while Venus Williams (6) fought off a second set challenge from Austria's Sybille Bammer to win 6-2, 7-5.
Vera Zvonareva (9), Daniela Hantuchova, Francesca Schiavone, Victoria Azarenka (7), Agnieszka Radwanska (10), Samantha Stosur (13) and Na Li also advanced to the third round.
Others who have booked their spots in the third round include wildcard Justine Henin -- who dismissed fifth seed Elena Dementieva, Kim Clijsters (15) and Svetlana Kuznetsova.