Ostapenko, who won 2017's French Open, is looking for her second ever WTA tournament win after rocketing to stardom with her Grand Slam win in Paris earlier this year. She is set to take on Nao Hibino in the next round.
Home favourite Na-Lae Han also advanced to the round of 16 after comfortably beating world No. 44 Kristyna Pliskova 6-4 6-4. However, she was unable to inspire fellow South Korean Su Jeong Jang to victory on the same court immediately after as American Nicole Gibbs won 6-3 7-5.
Elsewhere, Denisa Allertova beat world No.105 Andrea Petkovic 6-2 7-5 and Richel Hogenkamp emerged victorious in an all-Dutch battle with Kiki Bertens. Hogenkamp, who reached the second round of the French Open this year, came from behind to win 5-7 6-4 6-3.
American Christina Mchale ended the day's proceedings on court two after losing to Arantxa Rus 6-3 6-4.