Ninth seed Agnieszka Radwanska was beaten by Australia’s Ashleigh Barty in the last 16 of the Wuhan Open.
Radwanska, 28, rallied to dominate the second set and force a decider but Barty progressed 4-6 6-0 6-4.
The Pole’s ranking has fallen from world number three at the end of 2016 to 13 before the event in China.
World number 37 Barty knocked Great Britain’s Johanna Konta out in the last 32 and now faces Karolina Pliskova after her 6-2 6-1 win over Qiang Wang.
Barty and Pliskova are in the same half of the draw as Garbine Muguruza and could could face the world number one in the semi-finals.
Muguruza plays Poland’s Magda Linette in the last 16 on Wednesday.