Defending champion Caroline Wozniacki has survived dropping the first set to overcome Shelby Rogers and secure a place in the Pan Pacific Open quarter-finals.
Former world No.1 Wozniacki trailed 3-0 in the decider before securing a victory a 4-6 6-1 6-4 win after toiling for more than two hours on Thursday.
Pulling off an upset seemed on Rogers' mind as the American fended off three break points in the 10th game to clinch the first set.
Wozniacki wrestled back momentum in the second, converting two break points before firing back-to-back aces to force a decider.
Rogers raced to a 3-0 lead in the third set before Wozniacki staged a brilliant comeback, claiming six of the last seven games to advance to the next round.
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"I knew she has powerful strokes and a big serve. it definitely was not easy," Wozniacki said in a courtside interview.
"I'm just happy to win this one."
The Dane's next opponent is Slovakian fifth-seed Dominika Cibulkova, who accounted for Czech Katerina Siniakova 6-2 6-2.
Earlier, Barbora Strycova registered her first win over a top 10 player this year when the Czech edged out Britain's Johanna Konta 7-5 7-6 (7-5).
"I'm very happy, because this match meant a lot to me," Strycova said.
"I don't have any words to say because I'm very emotional and very happy that I won against Johanna.
Ninth-seeded Caroline Garcia beat local favourite Kurumi Nara 6-1 6-3 to set up a quarter-final clash with world No.1 Garbine Muguruza.
