WUHAN • Agnieszka Radwanska has been taking sleeping pills at night to help her rest. Yesterday, she found more reasons to lose sleep, after her 1-6, 7-6 (11-9), 4-6 loss to Svetlana Kuznetsova in the Wuhan Open quarter-finals.

The defeat meant that the 27-year-old Pole has to wait for at least another week to secure her qualification for the season-ending WTA Finals Singapore, where she is the defending champion.

The world No. 4 needed to win the Wuhan title to book her sixth straight appearance at the WTA Finals, which will feature the eight best singles and doubles pairs of the season.

The loss to Kuznetsova, the world No. 10, was Radswanka's fourth defeat in six meetings against top-10 players this year.

Earlier, world No. 5 Simona Halep became the third singles player after Angelique Kerber and Serena Williams to book her spot in the Finals, when she ousted American Madison Keys 6-4, 6-2 to advance to the last four.

It will be the Romanian's third consecutive appearance at the Singapore Indoor Stadium. In 2014, she finished runner-up to Williams, but failed to get past the group stage last year.

Halep feels she deserves a place in the elite tournament, having won three Women's Tennis Association titles this year, including the Madrid Open and the Rogers Cup.

The 2014 French Open finalist said: "I feel that I deserve to be there. Of course, I have not won a Grand Slam yet, but I still played well in the big tournaments."

Alvin Chia