Sir Ranulph Fiennes has completed the first stage in his bid to become the oldest Briton to complete the Marathon des Sables - a gruelling six-day ultra-marathon in the Moroccan desert.
The explorer, who turned 71 in March, faces temperatures of more than 50C and endless sand dunes in a challenge dubbed the toughest foot race on Earth.
It covers 155 miles including the distance of a marathon a day and a double marathon one day, with runners carrying everything they need on their backs.
A spokeswoman for Sir Ranulph said he had completed the first stage yesterday, from Jebel Irhs in the south Moroccan Sahara, covering 22.49 miles.
She said: "He finished the run in eight hours, after battling the extreme heat, uphill climbs and sand dunes.
"The route started across rocky terrain but soon moved into a small jebel (mountain) climb. At 22k Sir Ranulph crossed a dune field followed by a long, arduous ascent under the burning midday sun."
Sir Ranulph said: "It was a tough day, going up the dunes is the hardest part, especially under the midday sun. My shoulders are sore from the pack and my right foot needs looking at. I'm not thinking about tomorrow until tomorrow."
He is raising money for charity Marie Curie.
He is embarking on the challenge despite having suffered two heart attacks, undergoing a double heart bypass, a cancer operation and fighting diabetes.