Brazilian star Beatriz Haddad Maia has proved too powerful for Anna Tomljanovic, beating the Australian 6-3, 6-4 to advance to the WTA quarterfinals in Seoul. 

Haddad Maia broke Tomljanovic's serve three times on her way to the last eight of the Korea Open, where she will meet Polina Kudermetova.

Tomljanovic had been involved in a three-hour struggle against South Korean wildcard Su Jeong Jang in the previous round, eventually winning 7-6 (7-4), 4-6, 6-3.

But against the No.3 seed she came up short, double-faulting three times and managing to convert just one of three break points.

Joining Haddad Maia in the quarterfinals of the WTA 500 event on Thursday were Daria Kasatkina, Emma Raducanu and Viktoria Tomova.

Top-seed Kasatkina beat American Hailey Baptiste 6-4 6-2 while Englishwoman Raducanu upset No.8 seed Yue Yuan 6-4 6-3, dishing out 11 aces.

Tomova led 7-5 4-1 against Amanda Anisimova when the American retired.

Joining Russian Kudermetova in the last eight are her sister Veronika Kudermetova, Diana Schnaider and Marta Kostyuk.

AAP