Caroline Wozniacki battles to victory in Tokyo

Denmark's Wozniacki came through 7-6 (7/4) 4-6 6-4 in just short of three hours against her Spanish opponent in a rain-delayed match.

World number 28 Wozniacki, who won the tournament in 2010, admitted the delay early in the final set had worked in her favour.

"I won the next three games after the rain and managed to regroup. She was on a bit of a roll so it came at a good time," she was quoted on the WTA's official website.

"This was such a tough match, we played for such a long time and we really both deserve to be here as winners as the standard was very high."

Wozniacki will meet either Yulia Putintseva or Magda Linette in the quarter-finals, while second seed Agnieszka Radwanska will take on Puerto Rico's Olympic gold medallist Monica Puig.

Radwanska was made to fight all the way by Czech Barbora Strycova before coming through 6-3 3-6 7-5, while Puig hit back from a set down to upset seventh seed Petra Kvitova 1-6 6-4 6-4.

Japanese teenager Naomi Osaka, world number 66, delighted the home crowd as she knocked out sixth seed Dominika Cibulkova 6-2 6-1.

Top seed Sara Errani crashed out of the Guangzhou International Women's Open in China after losing 7-6 (9/7) 3-6 4-6 to Swiss world number 67 Viktorija Golubic.

Golubic, 23, won in just under three hours and will play Anett Kontaveit in the last eight after the Estonian ended home interest by beating China's Lin Zhu 6-1 3-6 6-0.

Second seed Jelena Jankovic stayed on course to defend her title after second-round opponent Rebecca Peterson was forced to retire early in the second set while trailing 6-1 1-0.

Jankovic will now face Sabine Lisicki for a place in the semi-finals after the big-serving German , currently ranked 213 in the world, beat Chinese qualifier Shuai Peng 6-4 6-1.

Croatian third seed Ana Konjuh defeated Georgian qualifier Sofia Shapatava 6-1 7-6 (7/2) to set up a last-eight clash with unseeded American Jennifer Brady, who came through against Montenegro's sixth seed Danka Kovinic 6-3 7-5.

American Alison Riske, seeded fifth, outlasted Olga Govortsova of Belarus 2-6 6-2 7-6 (7/1) and will take on unseeded Ukrainian Lesia Tsurenko, who beat Nigina Abduraimova 6-2 6-2.

Swedish second seed Johanna Larsson will play Lara Arruabarrena for a place in the semi-finals at the Korea Open in Seoul.

Larsson recovered from a second-set wobble to defeat Ukraine's Kateryna Kozlova 6-3 1-6 6-2 and Spaniard Arruabarrena came through a marathon three-set encounter with unseeded American Louisa Chirico 4-6 7-6 (7/4) 7-6 (7/2).

Italy's Camila Giorgi beat Belgian Mona Barthel 2-6 6-1 6-4 and will play China's third seed Shuai Zhang, who knocked out American Bethanie Mattek-Sands 6-3 7-5, for a place in the last four.