Top seeds Simona Halep and Petra Kvitova have won through to the semi-finals of the Shenzhen Open tennis tournament in China.
Top seed and world No.3 Simona Halep breezed past Serbian qualifier Aleksandra Krunic in straight sets on Thursday to reach the semi-finals of the Shenzhen Open tennis tournament in China.
Halep, last year's French Open runner-up, made short work of her opponent, winning 6-3 6-3 in 62 minutes.
In the semi-finals, she will face Chinese player Zheng Saisai, 20, who is ranked 97th but beat fourth seed Zarina Diyas of Kazakhstan 3-6 7-6 6-2.
Former world No.2 Vera Zvonareva's injury devils returned to haunt her as she lasted just 29 minutes in her first WTA quarter-final since 2012 before retiring in tears.
Zvonareva reached the Wimbledon and US Open finals in 2010 but has since been plagued by injury and illness, dropping to 250 in the world, and was attempting to launch a 2015 comeback at the $US500,000 ($A541,0000) tournament.
Swiss eighth seed Timea Bacsinszky, ranked 47 -- who is Zvonareva's doubles partner -- had already broken her once.
In her semi-final, she will meet second seed and world No.4 Petra Kvitova, who has downed Tereza Smitkova 7-5 6-4 in an all-Czech encounter.