An extreme adventurer from Cheltenham is due to set off on a 4,500-mile cycle ride across Europe.
Sean Conway, 36, is hoping to break the world record by cycling from Portugal to Russia in less than 25 days.
The world record did stand at 29 days, 18 hours but Mr Conway said "four days were wiped off the record" a week ago.
He said: "It's gone from difficult-but-doable to really tough. I've got to be doing a good 170 miles a day if I'm going to get it under 25 days."
The ginger-bearded athlete will ride from Cabo de Roca in Portugal to Ufa in Russia - more than double the 2,200 miles covered over 23 days in the Tour de France.
He will also be completing the challenge unsupported, meaning he will be going it alone and carrying all of his kit with him along the way.
"I'd like to spend a minimum of 16 hours a day out on the road and if I could have a good six hours sleep, I should be recovered," he said.
"But as my luck would have it, Europe is going through a crazy heatwave and it's also pretty windy, so not the ideal starting conditions I was hoping for."
He will also be relying on the people he meets across Europe to help him, especially in remote places where he may be without food or water for several days.
"I do have the thing of the Alps being in the way but my route is going to take me north of the Alps," he said.
"The shorter route would be straight through but - whether it works or not - I've chosen to add more mileage rather than doing the Alps."
This is not the first time Mr Conway has taken on an endurance challenge.
In 2016 he completed a 4,000-mile continuous "ultra-triathlon", swimming, running and cycling around the coastline of mainland Britain.