Beijing - World number six Agnieszka Radwanska of Poland beat Russia's Elizaveta Kulichkova at the Tianjin Open on Friday, setting up a semi-final clash with Czech Karolina Pliskova.
Second seed Radwanska won 7-6, 6-2 in an hour and a half, while third seed Pliskova beat Hungary's Timea Babos 6-3, 6-2.
Fifth seed Kristina Mladenovic of France was knocked out, however, by Serbia's Bojana Jovanovski 6-4, 4-6, 6-3.
The winner of the Radwanska-Pliskova match will play either Jovanovski or Danka Kovinic of Montenegro, both unseeded.
The $500 000 WTA tournament has seen a run of upsets, the most spectacular when Italian top seed Flavia Pennetta, who won the US Open last month, went out to a player ranked more than 400 places below her, Ukraine's Lyudmyla Kichenok.