Jelena Ostapenko's defence of her Korea Open title was ended in the second round by Ekaterina Alexandrova, for whom the exertions proved too great as she went on to be hammered by Hsieh Su-wei later on Friday.

Rain on Thursday meant top seed Ostapenko, who won this WTA International event by coming from behind to beat Beatriz Haddad Maia 12 months ago, was made to wait for her last-16 meeting.

And the Latvian was broken five times as her unseeded opponent wrapped up a 6-3 6-2 success - her first against a top-10 opponent.

But that was as good as it got for the Russian, who took on Hsieh in the last quarter-final and was thrashed 6-0 6-1 in just 51 minutes.

Hsieh is through to a semi-final meeting with Ajla Tomljanovic, who got the better of a see-saw deciding set to overcome Mandy Minella 6-2 4-6 7-5.

The other last-four clash sees Kiki Bertens take on Maria Sakkari after the second and third seeds defeated Evgeniya Rodina and Irina-Camelia Begu respectively.

Bertens recovered from a set down to bagel Rodina in the last and seal a 3-6 6-3 6-0 win while Sakkari also went the distance before advancing 6-3 4-6 6-4.

Meanwhile, in China, the Guangzhou Open final will be contested between Wang Qiang and Yulia Putintseva. The home favourite ousted Andrea Petkovic 6-2 6-2 and Putintseva was similarly comfortable in dispatching Bernarda Pera 6-1 6-4.