The American top seed fell 6-7 (3), 6-1, 6-2 to Russia’s Kuznetsova in a 122-minute battle to lose prior to the quarter-finals in Miami for just the second time in her career.

Williams, who was targeting a remarkable fourth consecutive Miami crown and ninth overall, has not won a trophy so far this season and enters the clay court stretch title-less for the first time since 2012.

After splitting the first two sets, Williams went down a double break 0-3 in the decider.

She got one of the breaks back but Kuznetsova regained the advantage and closed out the match on a long ball from Williams, the 50th unforced error of the clash from the American.

“It’s obviously disappointing, but I’ve won here a lot, so it’s okay,” said Williams, who struck nine double faults.

The 34-year-old, who is based in Florida and trains there regularly, did not blame the heat and tough conditions for her surprise exit but admits her movement was sluggish.

Asked to elaborate on why she was unable to bring out her best, Williams said: “I don’t think it’s
appropriate to criticise my movement right now. I did the best that I could. I can’t win every match. The players come out and play me like they’ve never played before in their lives. You know, the best that I could do today. I have to be 300 per cent every day, so…”

Kuznetsova, who is now 3-8 lifetime against Williams apologised to the crowd for taking out their home favourite. “I’m sorry to the fans who are disappointed that Serena is not going to keep playing but for sure she will have more wins here,” said Kuznetsova.