Olympic champion and adventurer James Cracknell is in hospital with a head fracture after being knocked off his bike in the US.
The BBC reports that a spokeswoman for Cracknell said: "He is conscious and his condition is stable. Doctors have said he is making very good progress."
The 37-year-old, who is in Arizona filming for the Discovery Channel, was hit from behind by a truck.
His wife, TV presenter Beverley Turner, is with him in hospital.
Close friend Ben Fogle said on Twitter, "James has been in a cycling accident in the US. My thoughts are with James and his family. Flying out to Phoenix hospital tomorrow."
Cracknell and Fogle had been due to start a bike race from Canada to Mexico, but that is now on hold.
Cracknell was just a week into his latest challenge: cycling, swimming and running across the North American continent in just 18 days. Just before setting off, Cracknell outlined the challenge on his website: “Starting this week [15th July 2010] I'm going to be doing a kind of greatest hits of the States with Discovery Channel - Cycling 264miles from Santa Monica into Death Valley and I'll then be running 80miles through Death Valley.
“Twenty or so hours later I'll hop (or rather limp) back on the bike to cycle Route 66 for 2,500miles to Toledo and Lake Erie. I'll row the Great Lake; disembark at Buffalo to remount my trusty steed for the 500miles to Manhattan, ending with a 15mile swim down the Hudson towards the Statue of Liberty. The aim is to do it in about 18 days, hmm.”