Heather Watson saved four match points before beating Magda Linette in a contest to keep her run at the Tianjin Open.
The British No 2 is through to her first WTA Tour semi-final in over a year after living a topsy-turvy competition to prevail 7-5 6-7 (4-7) 7-6 (8-6) in 3 hours and 2 minutes.
It was by far the best week of a typically miserable period for Watson along with the success guarantees next week, she will go back to the top 100.
Watsons second-round success over Wang Qiang has been her most impressive for two or more decades and in Linette she confronted a participant who has had a fine season.
While in Beijing she dropped just three matches in a qualifying game to Watson, the Pole won her first WTA title and reached the final in Seoul last month.
Having won the first sets past five games, Watson had a match point when operating in the second but Linette stored it levelled the contest.
The seed subsequently had four chances to win the match on Watsons serve at 4-5 in the decider, but each time that the 27-year-old stood business and she took her third match point in the deciding tie-break.
Watson will face either Veronika Kudermetova and also even the third seed at the semi-finals.