Now that Novak Djokovic has ended the seven-year, five-month world No 1 duopoly of Rafael Nadal and Roger Federer, the tennis planet is free to address the next burning question: who will end the Nadal-Djokovic duopoly, which is at 57 weeks and counting?
It is hard to imagine, in an era of "one guy or the other" at the top, but four players (Lleyton Hewitt, Andre Agassi, Juan Carlos Ferrera, Andy Roddick) fought their way to No 1 in the space of a tumultuous half year, in late 2003.
At present, Djokovic and Nadal are so far ahead of the rest that they could go on holiday for a month and keep their 1-2 spots.
Identifying the men who could climb over them to the top would seem to call for an examination of those of a certain age, 24 or under, who already have shown a capacity for winning tournaments.
Andy Murray is top of the list. At 24, he retains room for improvement. Also, at No 4 in the world, he already has a significant points platform from which he can campaign for the top.
Not that it would be easy. It remains very difficult to be No 1 without winning a grand slam, and Murray has never won one. No British man has since 1936.
Still, he is close enough to the summit to make an attack. If he can win every tournament he enters until, say, the Australian Open, he could be there.
It probably is safe to dismiss those behind Murray in the top 20 who are closer to age 30 than age 20, and there goes everyone aside from Juan Martin del Potro.
The towering Argentine, 22, might have the right stuff. A huge serve. Surprising athleticism. One grand slam (the 2009 US Open) already on his CV and a semi-final run in the French Open, which seems to demonstrate multi-surface capability. If he can stay healthy, he bears watching.
If it is assumed Djokovic or Nadal will be No 1 for another year or three, examining the credentials of players with more promise than championships makes sense.
Potential climbers among that group include Milos Raonic, 20, the big-hitting Canadian; Marin Cilic, the 22-year-old Croat who has been ranked as high as No 9; and Ryan Sweeting, 23, a rare American who is effective on clay.
Perhaps the most promising of all the young guys is Bernard Tomic, the 18-year-old Australian who made a run to the Wimbledon quarters, ousting Robin Soderling and Nicolai Davydenko en route.
One other man bears following. He has history of success against the top two, he never leaves a tournament early and he has lost only three times this year to someone not named Djokovic or Nadal.
He has been No 1, lost it, and regained it. Federer may be on a slow decline, but if he has one more surge in him, the next outsider to be No 1 could be the ultimate former insider.