How do you rate the greatest athlete of all time - according to number of wins, athleticism, longevity, stepping up on the big stages, domination of their sport at a time of champions?
It's an argument that could never be solved in a bar.
But throwing all those in, there's a case for surfer American Kelly Slater's ninth world championship win earning him a top spot in a best 10.
In the other corners boxer Muhammed Ali, cyclist Lance Armstrong, golfer Tiger Woods, football star Pele, Formula One driver Michael Schumacher, Finnish Olympian Parvo Nurmi, basketball great Michael Jordan, swimmer Michael Phelps and A. N. Other, your choice.
Slater was the youngest to win the ASP world title in 1992, aged 20, and is now the oldest to win it at 36. To show how tough that is, no one else has won more than four titles. Slater has 39 wins all up, beating Australian Tom Curren who retired on 33.
He recorded two perfect 20 out of 20 scores at Teahupoo in Tahiti, regarded by all surfers as the world's heaviest wave, the only person to get 20 there.
He won five straight between 1994-98, and retired citing burn-out then returned in 2003, lost to Andy Irons that year and in 2004 and has now won four straight.
With two rounds to go on the Association of Surfing Professionals world tour, Slater has an unassailable 1850 points lead over his nearest rival. No doubt he'll underline his domination in the last event, one of his favourites, the Pipeline Masters.
Ali certainly fought at a time of champions, unlike the chumps in the heavyweight division now.
It's true he would not have been as great had it not been for Joe Frazier, George Foreman, etcetera, but he did not continually dominate those. For his humanitarian work he may certainly be the greatest sportsman ever.
Armstrong has seven wins in the world's toughest cycling race, but just one world championship.
Tiger Woods' 14 majors and 65 PGA tour wins, second only to Jack Nicklaus, put him in the mix and he certainly earns more, US$122 million ($204 million) in 2007 from winnings and sponsorships. But he doesn't compete in terms of fitness, strength, agility, co-ordination.
Pele dominated in a team game.
How do they measure those against individual performance in the "best athlete" category?
Schumacher enjoyed dominant machinery to drive him to seven world championships.
The 1920s Finnish runner Nurmi is generally regarded as the greatest Olympian for his haul of nine gold medals and three silvers from 12 events at three Games but do his events compete against surfing for all-round athleticism?
Swimmer Phelps has variety within the discipline of swimming in his Olympic haul, taking the individual medleys in his haul of eight golds at Beijing to prove total superiority in the pool by eclipsing Mark Spitz's seven golds achieved in two strokes, freestyle and butterfly, Phelps' gold total 14 and a games to come.
But he competes on flat water, just having to beat the other contestants, not nature as well.
Surfing is an incredibly physically demanding sport. And there's the fear factor - surfers often get cut like boxers, they can get slammed like drivers in car crashes.
But Slater is self-described as "the luckiest man in the world" - and many might agree given his dating of the likes of Cameron Diaz and Gisele Bundchen.
But luck has nothing to do with nine world titles.