In short:

Maya Joint has defeated Romania's Sorana Cirstea at the Pan Pacific Open event in Tokyo.

Joint entered the tournament ranked world number 94, 78 places lower than Cirstea.

What's next?

Joint advances to the round of 16 where she will face Spain's Cristina Bucșa.

Maya Joint has made a mockery of the tennis rankings with an impressive display to uproot one of the top seeds at the Pan Pacific Open event in Tokyo.

Ranked a career-high 28 in February, the Australian's ranking has dropped steadily throughout the year, and she entered this WTA 500 event ranked 94th.

However, the American-born Aussie showed the numbers can't always be trusted as she powered past sixth seed and world number 16 Sorana Cirstea of Romania.

Joint's impressive 6-3, 7-6 (7-4) victory yesterday secured her a spot in the round of 16.

It also continued her recent resurgence, after she made the final at last month's Korea Open in Seoul, where compatriot Kim Birrell claimed her first WTA title with a 6-4, 6-2 win in the final.

Joint's next opponent is Spanish world number 42 Cristina Bucsa, who beat France's Diane Parry 7-5, 6-1 yesterday.

And Joint isn't the only in-form Australian still in the main draw.

On Monday, Talia Gibson, who recently reached the Singapore final, came through an all-Australian affair over qualifier Daria Kasatkina 6-0, 7-5.

Gibson powered through the first eight games in a row but was made to work hard to hold off the former world No.8 in the second set.

Her reward is a round-of-16 clash with eight-seeded Aleandra Eala, of the Philippines.

Meanwhile, in the Guangzhou Open, Venus Williams lost 6-2, 6-2 to Austrian teenager Lilli Tagger to be 0-13 in singles this year. The 28-year age gap between Williams, 46, and Tagger, 18, is believed to be a record difference between opponents in a WTA Tour match.

Williams created no break-point chances, and Tagger took four of the 16 she had.

AAP