Caroline Wozniacki made to work for Tokyo win
World number one Caroline Wozniacki survived a fightback by Jarmila Gajdosova to ease into the third round of the Toray Pan Pacific Open in Tokyo.
The Dane won the first set 6-1, but then lost the second on a tie-break.
Wozniacki fought back to claim the third 6-3 and set up a third-round encounter with Estonia's Kaia Kanepi, a 6-2 6-2 winner against Coco Vandeweghe.
The victor will face either Jelena Jankovic or Agnieszka Radwanska in the quarter-finals after the Pole gained revenge for US Open second-round defeat by Angelique Kerber.
Radwanska came from a set down to beat the 33rd-ranked German 3-6 6-3 6-3.
There was a shock as US Open champion Samantha Stosur lost 6-2 4-6 6-4 to Maria Kirilenko. The Russian will now face Serbia's Ana Ivanovic after she saw off Britain's Laura Robson 7-5 6-4 in a tight match.