Discounting the Williams sisters before they are well and truly retired continues to be a dangerous occupation.
Just when it seemed as if Venus, at least, had gone round the career bend due to age, injuries and a serious medical condition, she has found new inspiration, parlaying a wild-card entry into the final 16 of the Sony Ericsson event in Miami.
Injuries to her hip and abdomen cut into the first half of her 2011 season, and in the summer she was given a diagnosis of Sjogren's Syndrome, an energy-sapping auto-immune disease.
Her season ended after only 11 matches. She had not played a tournament in seven months when the Miami masters began last week, and her world ranking had fallen to No 134.
Three victories later, including a three-set, three-hour conquest of the No 3 seed Petra Kvitova, sent Venus into a compelling match today against Ana Ivanovic, another former world No 1.
Venus, 31, has confided that her primary inspiration is rings, specifically, London 2012 and the five Olympic rings. "Whenever things look bleak, I think about the Olympics and that keeps me motivated," she said after another three-hour victory, over Aleksandra Wozniak, on Sunday.
Venus won gold in singles and doubles at Sydney in 2000, and teamed again with sister Serena to win doubles gold at Beijing 2008.
She is not the first athlete to be intoxicated by the lure of the Olympics, but those most in love with the Games tend to come from less-prominent sports.
She told reporters on Sunday that the Olympics is the "ultimate experience" in sports, and this is a woman who has seven grand slam titles, including five at Wimbledon. She wants one more bite of the Summer Games apple.
"It's a lot of hard work to come back to this level, especially, you know, with the time constraints," she said.
"I need to play now so I can play the Olympics. It's like I have to get back. Something's gotta give."
Her sense of urgency comes from the system used to issue Olympic invitations; the top 48 players in the world are awarded berths in the singles tournament, with a limit of four per country. If she goes deep into the draw in Miami and, perhaps, at Roland Garros, her ranking could soar.
Of immediate concern is the energy she expended in defeating Kvitova and Wozniak. She conceded she was exhausted after the latter match, in which she fought off a match point before winning 4-6, 6-4, 7-6.
The auto-immune disease can make her lethargic even when she is well rested. But no one who has been paying attention over the past decade will count her out. Ivanovic, certainly, will not.