TIANJIN, China – Agnieszka Radwanska stunned Tianjin when she withdrew from the tournament with a right thigh injury – shortly after showing just why she was the top seed.

The defending champion had taken Evgeniya Rodina apart, 6-1, 6-1, to progress to the quarterfinals, where she was to face Peng Shuai.

The Chinese wildcard had earlier beaten qualifier Chang Kai-Chen of Taipei 6-3, 6-2.

Radwanska is also the defending champion at the BNP Paribas WTA Finals Singapore presented by SC Global. “It’s the end of the season – I guess everyone is struggling with something,” she said afterwards.

She added that the injury had worsened over time and that she had decided to withdraw in order to give herself the best chance of recovering in time for Singapore.

“I’m very sorry I had to withdraw…I just hope I can see my fans [here] next year — it was a pleasure to come here again,” she said.

Olympic gold medalist Monica Puig had a straightforward time of it, beating Lara Arruabarrena of Spain, 6-4, 6-2.

Alison Riske also progressed in straight sets – but Poland’s Magda Linette did her utmost to take it to a decider, eventually losing out on a tie-break, 6-3, 7-6(2).