Newcastle and England football legend Alan Shearer and BBC presenter Adrian Chiles have started their gruelling Sport Relief challenge.
Alan Shearer and Adrian Chiles are cycling for Sport Relief
The duo are attempting to ride 335 miles from Newcastle to London, via West Bromwich, in only two days.
Newcastle boss Kevin Keegan started the Sport Relief Super Cycle at 0840 GMT at St James' Park on Thursday.
Shearer and Chiles hope to pedal into BBC Television Centre in London as part of Friday's live Sport Relief show.
"The professional cyclists think Adrian and I are mad," admitted Shearer.
"They don't understand why we are even contemplating our challenge because, in cycling terms, it's the equivalent of running three marathons in two days.
Shearer and Chiles will cover 335 Miles for Sport Relief
"But we've both visited projects that Sport Relief money supports and seen what a massive difference it makes, so although it'll be a massive test of our endurance we're determined to give it our best shot."
The pair are scheduled to pedal an eye-watering 186 miles on the first day and an energy-sapping 149 miles on day two.
Given that 149 miles is the maximum distance cycled in any one day of the Tour de France, Shearer and Chiles will really be up against it for Sport Relief.
They will travel to London via the Hawthorns, the home of Adrian's beloved West Bromwich Albion.
And you can show your support by making a donation to Sport Relief.
This year the big Sport Relief buzz word is 'challenge' and the idea is for everyone to do something sporty to raise cash.
Alan Shearer has visited a Sport Relief project in Uganda
So if you have been inspired by Shearer and Chiles or the extraordinary efforts of James Cracknell, who rowed, cycled and swam his way to Africa, why not challenge yourself for Sport Relief?
The ultimate way to get involved is to take part in one of the Sainsbury's Sport Relief Miles, which are happening across the UK on Sunday.
This year, participants can set their own challenge by having the choice of completing one, three or six miles. You can still sign up for the 23 Flagship Sport Relief Miles, but sign up closes at midnight on Thursday so you should sign up now.