Comedian Eddie Izzard blamed "medical complications" after he pulled out of a bid to run 27 marathons in as many days.
Izzard had finished four of the 26-mile runs before announcing today that he had been forced to quit, via on online message.
He wrote: "Having completed four marathons, unfortunately, I have had to put my attempt on hold due to unforeseen medical complications that have arisen due to a multitude of factors including severe terrain, humidity and altitude."
The schedule of 27 marathons, which had each been due to take place in South Africa, were intended as a tribute to former South African president Nelson Mandela and his 27 years spent imprisoned during the Apartheid regime.
Izzard was also raising money for disadvantaged people in the African nation.
Despite stating that he was "very sorry to let everyone down", the 50-year old pledged to complete the marathons at a later date:
"I wish to say that my attempt is not over and I will return to South Africa and run the 27 marathons and finish this story. I owe that to Nelson Mandela, who has inspired the world to struggle and succeed no matter what obstacles are thrown at us."
Back in 2009 Izzard completed 43 marathons in 51 days to raise money for charity Sport Relief. He received a special award at the BBC Sports Personality of the Year 2009 ceremony for his achievements.