Top women's seeds make early exits

World No 2 Simona Halep lasted less than a set before an injury forced her out of the China Open on Sunday, plunging her appearance at the year-ending WTA Finals into doubt.

Halep and Petra Kvitova, who was playing on painkillers and suffering the ongoing effects of glandular fever, both crashed out as the China Open lost its top two women's seeds in the opening round.

Romania's Halep said she would now take a break from tennis and assess if she can play the season finale in Singapore after retiring at 5-4 down in the first set against Lara Arruabarrena.