Kuznetsova hammers Venus in Wuhan

The veteran, seeded sixth and winner in 2015, was no match for the Russian, who completely overpowered Williams in a 6-2 6-2 win in China.

It was always going to be a tough ask for to retain her title after a patchy year but she had no answers.

"It just definitely wasn't the best day on the court," she said. "She played really well. Total credit to her for showing up. I think she just played well. Not every day is your day."

Fourth seed Simona Halep put herself within one win of booking a place at the WTA Finals later this month as she breezed into the quarter-finals.

The Romanian had little trouble in dispatching Yaroslava Shvedova 6-3 6-3 and she will now meet Madison Keys in the last eight.

Keys beat Russian qualifier Daria Kasatkina 6-1 4-6 6-4 to enhance her chances of making the end-of-season showpiece in Singapore while there was a similarly important win for Johanna Konta, who beat Carla Suarez Navarro 7-5 7-6 (8/6).