Mr Ravilious hopes to become the first to run the route non-stop

Rob Ravilious began on Saturday, hoping to do the 106-mile (171km) route from Winchester, Hampshire to Eastbourne, East Sussex, in less than 24 hours.

But 28 hours later the 30-year-old from Guildford, Surrey, is still running, despite picking up an ankle injury.

His running partner pulled out earlier, while another joined late on Saturday.

Chris Miller, 37, from Oxford, arrived to support his friend's challenge through the night, with 35 miles (56km) to go.

I'm feeling shot to bits Rob Ravilious

Mr Ravilious told the BBC News website: "It's tough work at the moment, a lot of limping, sheer pig-headedness is getting me through.

"I'm feeling shot to bits. During the night I felt trippy. I would have had a tough time if Chris hadn't joined me.

"We're going over the Seven Sisters cliffs in an hour, which is particularly hard going if you're hobbling around."

Mr Miller said: "I just really didn't want Rob on his own overnight so I stepped in. He's done amazingly well."

The pair hope to reach the post marking the end of the South Downs Way on Eastbourne seafront by Sunday afternoon.

Fundraising run

They are running unsupported, carrying their own clothes, water and food - including energy bars and pepperoni sticks.

Gordon Elliot, from Sawbridgeworth, Hertfordshire, abandoned the run after seven hours after suffering fatigue and an inflamed ankle.

He and Mr Ravilious attempted the same route non-stop before but stopped after 70 miles because of exhaustion and bad weather.

The latest attempt is in aid of the Naomi House children's hospice in Winchester, which relies on voluntary donations of �2.5m a year to provide respite and terminal care for children in the South.