Kristian Gkolomeev is back in Las Vegas this weekend with a shot at another fast payday and another time that would make headlines everywhere except the record books. The Greek swimmer will race on Sunday, Monday morning AEST, in the Enhanced Games and try to break Cam McEvoy's 20.88 world record in the 50-metre freestyle.

Gkolomeev already knows what the event can pay. Last year, in a 50-metre freestyle race staged for a documentary, he stopped the clock at 20.89, just inside the previous world record of 20.91 set by Cesar Cielo in 2009. That swim made him an instant millionaire, and he now says a time of 20.87 or faster would bring him a further $US1 million bonus and a $US250,000 winner's cheque.

For a swimmer who says he was making little money before the Enhanced Games, the numbers explain why he is back. Gkolomeev said, "It was a lot of money," and added that, as a swimmer before, he could not really support his family. He said he invested the money in his wife's nature school business and added, "I wish athletes were paid more. It was a huge help for me and my family."

That gap between elite performance and elite pay is part of what makes the Las Vegas event so easy to sell to athletes and so hard to defend to the rest of sport. McEvoy earned about $US10,000 for his recent victory in China and received no bonus for lowering the world record. Winners at last year's swimming world championships collected $US20,000 per event, while Proud said, "In theory, you'd have to win 22 or 23 world championship titles to get what you can earn in one night here."

Gkolomeev will swim alongside Great Britain's Ben Proud and Australia's James Magnussen, two more names drawn into an event that lets athletes use banned substances in normal sport under medical supervision for a one-day event. Proud signed with the Enhanced Games in September and finished second behind McEvoy at the Paris Olympics and last year's world championships. Gkolomeev said Magnussen was a big reason he joined the Games.

The event has triggered some of the sharpest criticism in modern sport. The World Anti-Doping Authority and the International Olympic Committee said in a joint statement that promoting performance-enhancing substances and methods sends a dangerous message, especially to current and future generations of athletes. They warned that such substances can lead to serious long-term health consequences, even death, and said no level of sporting success is worth such a cost.

Gkolomeev, for his part, has shown no sign of backing away from the gamble. He said, "I can sleep good at night. I'm not cheating or anything." He also said, "I'm not really worried about my health. We only go in a cycle through 10 weeks of taking substances … and only super-small doses."

The contradiction at the heart of the Enhanced Games is plain enough. It offers money and attention on a scale traditional swimming rarely matches, but any time recorded there will not be officially recognised. Gkolomeev's 20.89 last year was close to Cielo's old standard, and McEvoy has since edged it down to 20.88. If Gkolomeev goes faster on Sunday, the stopwatch will matter to the people in Las Vegas — but not to the sport's record books.