Alan Shearer and Robbie Savage will tackle each other in a five-day Sport Relief challenge to see who can sit on 45,000 Wembley Stadium seats in the fastest time.
Shearer Vs Savage: The Battle of the Backsides will see the pundits divvy up Wembley Stadium's 90,000 seats from March 10-14 and attempt the sit-off, with each aiming to be the first to complete 45,000 chairs and reach the winning post, the royal box.
Estimates suggest that they will have to manage around 14 seats per minute across 10 hours each day in order to complete the challenge by the time the final whistle blows.
Match Of The Day star Shearer said: "Even at the peak of my career this challenge would have been tough on my body. However, now I am a retired footballer - so it's going to be a challenge of physical and mental endurance. I can't let Rob win; I'd never live it down."
Savage added: "Alan does have an advantage as his butt is larger than mine - but my bottom is ready for the challenge."
To support the challenge, members of the public are being encouraged to enter a competition at www.sportrelief.com/backsides with the chance to win tickets to see England play at the 2014 World Cup in Brazil, a day watching tennis at Wimbledon or a chance to see One Direction playing on tour.