DUBAI - Venus Williams lost her title and an unbeaten record stretching back a decade when she subsided to a 6-4, 6-2 third round Dubai Open defeat against Lucie Safarova.
The 34-year-old American's serving delivery was at half pace for much of the match in a court temperature of about 40 degrees, her movement was slow, and her appetite for the battle not great.
Williams dropped serve in the opening game and after failing to convert three successive break back points at 4-5, no longer looked a serious contender for victory.
The result was more a surprise given that this was only Williams' second defeat this year, and that she may now have to wait a while before returning to the world's top ten after a four-year interval, one of her goals.
"Obviously I want to win and then your ranking goes up," she said.
"But I have been super happy with the year so far and I am disappointed to lose. She is a player who hits the ball a little bit different. I don't think I was playing badly."
Safarova's serve was certainly difficult to read, and she mixed in swerving deliveries into the body with others swung out wide, testing the reach on a right-hander's double-handed backhand.
She also hit confidently, and moved remarkably well considering she had had a three-hour match the previous day followed by a doubles.
"That's what you train for," Safarova said.
"I really felt well on court. It sometimes gives you extra confidence when you come close to defeat (against Casey Dellacqua of Australia) and you turn it around."
Safarova also claimed to have taken confidence from winning a Grand Slam doubles title at last month's Australian Open. She was due to play the winner of Ana Ivanovic, the former world number one from Serbia, and Karolina Pliskova, her rising 22-year-old compatriot.
Although Williams will return home earlier than expected after 16 successive wins in Dubai, it will not alter to her decision to continuing giving a miss to the Indian Wells tournament which starts in three weeks' time.
"It will give me a chance to rest," she said.
Her sister Serena Williams, the world number one, has by contrast agreed to return to the Californian event after a 14-year interval during which both sisters have boycotted the tournament - a response to hostile, allegedly racist, treatment from spectators.
Venus was quizzed about her attitude to this.
Asked if Serena had consulted her on this sensitive decision, Venus said: "You know, she didn't ask me my opinion. She just said, I might be playing there. I said, Oh, okay. That's pretty much the conversation."
And asked if she could understand the decision to let bygones be bygones, she said: "Um, I don't know. I just respect every decision she makes, pretty much. There's nothing complicated about it."
Venus was then invited to say whether she would consider returning to Indian Wells one day, to which she replied: "I haven't really given a lot of thought to it. I have just been focusing on this year."
Earlier Agnieszka Radwanska, a former titleholder, was also beaten.
The fifth-seeded Pole has been suffering from a virus and looked below par for the second successive day as she lost 6-4, 6-2 to Garbine Muguruza, a 21-year-old from Barcelona who looks en route for the top 20.
And later Flavia Pennetta, a wild card entry who saved four match points against Julie Goerges of Germany in the first round, followed it by winning 6-2, 3-6, 6-1 against the seventh-seeded Angelique Kerber, another German.