Elina Svitolina saved four match points to avoid a shock quarter-final defeat to qualifier Ons Jabeur at the Taiwan Open.
Top seed Svitolina, ranked 168 places above her unfancied opponent, raced through the first set in just 27 minutes, but had to stave off a brave comeback from Jabeur to triumph 6-1 3-6 7-6 (7-4).
In an erratic decider, Svitolina staved off a quartet of match points when serving at 5-3 down, and Jabeur twice failed to serve out the match before being outplayed in the tie-break.
"I think Ons played unbelievable," Svitolina said after the win. "I think I got a little bit lucky towards the end because she was playing so amazing."
Mandy Minella awaits in the semi-finals after she came from behind to defeat Zhu Lin 1-6 6-3 7-5.
On the other side of the draw, second seed Sam Stosur - who fought back against Dalila Jakupovic in the previous round - saw her hopes ended by Peng Shuai in a 6-4 6-4 defeat, while sixth seed Misaki Doi - a runner-up 12 months ago - crashed out 6-4 7-6 (7-1) to Lucie Safarova.