Daria Gavrilova had to fight hard in the second set but finally overcame Japan's Miyu Kato in a tiebreaker to join Samantha Stosur and Lizette Cabrera in the last 16 of the WTA Hong Kong event.
The world No.22 and seventh seed will now face American Shelby Rogers for a place in the quarter-finals.
But Kato made Gavrilova dig deep on Tuesday after the Australian breezed through the first set 6-1.
Gavrilova was up 5-3 in the second before her No.126 ranked opponent rallied to 6-6.
Gavrilova showed some of the form from her two wins in Beijing's China Open last week to finally take the set 7-6 (7-4) and match.
Earlier fourth seed Agnieszka Radwanska beat local wildcard Zhang Ling 6-1 6-2 to become Stosur's opponent in the second round.
Radwanska had failed to defend her title at the China Open last week, falling to the unseeded Daria Kasatkina 4-6 7-5 6-2.
But the Pole was in far better form on Tuesday.
"I'm just very happy to win my first match in Hong Kong," Radwanska said on court.
"Conditions are not easy, so I'm very happy to get through and win that match in two sets, ready for the next one."
Stosur holds a 3-1 advantage in meetings, winning their last match in the Carlsbad quarter-finals in California in 2013.
Cabrera had won her first round match on Monday.
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