World number three Radwanska, the top seed and defending champion in Shenzhen, looked set to triumph comfortably on Monday when she eased through the first set of her match against Duan Ying-Ying.

However, Duan - 100 places below her opponent in the rankings - levelled the match in a tie-break before coming from 3-1 down in the deciding set to move a break up at 5-4.

Three match points came the way of the Chinese as she served for a place in round two, but the gutsy Radwanska saved them all and ultimately completed a 6-2 6-7 (4-7) 7-5 win.

Second seed Simona Halep was also pushed hard by former world number one Jelena Jankovic, the Romanian eventually prevailing 6-1 3-6 6-3.

There was an easy success for Johanna Konta, though, as she beat Cagla Buyukakcay 6-2 6-0.

Timea Bacsinszky withdrew from the event due to an abdominal injury, while fellow seeds Timea Babos and Anastasija Sevastova suffered respective defeats to Nina Stojanovic and Kristyna Pliskova.

Camila Giorgi, Katerina Siniakova, Ons Jabeur, Chang Kai-Chen and Zheng Saisai were the other first-round winners.