Not content with outdoing the world's greatest long-distance runners twice in last year's Olympics and carrying the burden of favouritism into this year's world championships, Mo Farah has sought to make his life just a little bit more difficult by challenging the fastest man in history to a race over a mutually inconvenient distance.

Farah and Usain Bolt share an agent and a friendship, so the possibility of one of sport's more unlikely head-to-heads actually coming to pass cannot be discounted. "He's got his charity foundation, I've got the Mo Farah Foundation," Farah said. "It would be great to do a distance where people, proper athletics fans, vote in on what distance they think is most suitable."

Farah, the Olympic 5,000m and 10,000m champion, suggested that the fairest distance for him to face the man who took gold over both 100m and 200m at the last two Games would be between 600m and 800m. "Are you up for that?" he asked Bolt. "Come on, you've got to do it. Let's get it on."

Bolt sounded ready to take up the challenge. "It sounds like fun," he said. "It would be tough, but for charity. 600 would be better for me."

A previous attempt to tempt Bolt out of his comfort zone, when London 2012's record-shattering 800m gold-medallist David Rudisha challenged the Jamaican to a race over 400m, "for charity or as an act of healthy competition", was dismissed earlier this year.

But Bolt has previously shown a willingness to help Farah's charitable endeavours, having donated the shoes he wore in last year's 100m final to the Briton's foundation – and then auctioned them off himself at a gala dinner at London's Grosvenor House hotel, raising £39,000. "Me and Mo we go way back," Bolt said, after the pair celebrated together, each performing the other's famous celebratory pose, on the last night of Olympic athletics in 2012. "We have been through ups and downs."