Johanna Konta downed by Barbora Strycova in Tokyo

Konta, who had been given a bye in the first round, squandered a 3-0 lead in the first set and the British number one was also unable to convert two set points in the second in her first match since losing in the opening round at the US Open.

"I'm very emotional and very happy that I won against Johanna," Strycova said. "I tried to focus on every point. She's such a tough opponent to play, she doesn't give you anything for free, you have to work for it."

Former world number one Caroline Wozniacki recovered from a set down to defeat American Shelby Rogers and set up a quarter-final with Dominika Cibulkova, who enjoyed a 6-2 6-2 victory over Katerina Siniakova.

In the Korea Open in Seoul, top seed and French Open champion Jelena Ostapenko eased into the quarter-finals with a 6-2 6-2 victory over Nao Hibino, while fourth seed Sorana Cirstea dropped just two more games in beating Nicole Gibbs.

There were also wins for Priscilla Hon and Veronica Cepede Royg, the latter taking on Ostapenko in the last eight.

Belgium's Yanina Wickmayer continued her impressive form in the Guangzhou Open in China by defeating sixth seed Alize Cornet to reach the semi-finals.

Wickmayer, who knocked out top seed Peng Shuai in the previous round, beat Cornet 6-1 7-6 (7/5) and will face Aleksandra Kunic in the last four after the Serbian thrashed Rebecca Peterson 6-1 6-1.

Second seed Shuai Zhang, who has lost just three games in three matches, kept home hopes alive with a 6-1 6-1 win over Kateryna Kozlova and will face Evgeniya Rodina in the semi-finals. Rodina beat Lizette Cabrera 6-1 7-6 (7/4).