Shenzhen - American world number 39 Alison Riske stunned Polish top seed Agnieszka Radwanska in the Shenzhen Open on Thursday, sending her careering out of the WTA tournament 6-2, 3-6, 6-0.
Riske raced to a 5-0 lead in the quarter-final first set in the southern Chinese city before Radwanska, the world number three, offered brief resistance, breaking her opponent back once.
The defending champion secured the second set 6-3, but the decider was a demolition that belied the difference in their rankings, with Radwanska only winning six points and Riske taking it to love.
China is a happy hunting ground for 26-year-old Riske, whose only WTA tour victory came at the Tianjin Open in 2014 and who reached the final there again last year.
The highest-ranked player left in the $750,000 Shenzhen Open is Britain's world number 10 Johanna Konta, who ground out a 6-4, 6-7 (11/13), 6-3 victory over Kristyna Pliskova of the Czech Republic.
The two women hit a combined 22 aces during their two hour, 12 minute match, with Pliskova saving two match points in the marathon second set tie-break, and Konta four set points, before the Czech finally prevailed.
"I knew going into the match that I would have a tough challenge on her service games," said Konta. "I tried to neutralise her first and second serves as much as possible to try and get myself into those games, and work very hard to create some chances."
In Friday's semi-finals Riske will face Italy's Camila Giorgi, who eliminated home player Wang Qiang 6-0, 6-2.
Konta will take on Katerina Siniakova, who followed up her defeat of world number four Simona Halep by disposing of Serb qualifier Nina Stojanovic, 6-3, 6-4.Results from the WTA Shenzhen Open on Thursday (x denotes seeding):
Alison Riske (USA x8) bt Agnieszka Radwanska (POL x1) 6-2, 3-6, 6-0
Johanna Konta (GBR x3) bt Kristyna Pliskova(CZE) 6-4, 6-7 (11/13), 6-3
Katerina Siniakova (CZE) bt Nina Stojanovic (SRB) 6-3, 6-4
Camila Giorgi (ITA) bt Wang Qiang (CHN) 6-0, 6-2