There was a very special guest at Wembley on Tuesday as five-time Olympic gold medallist Sir Steve Redgrave showed up at the National Stadium to throw his support behind Alan Shearer and Robbie Savage’s Battle of the Backsides Sport Relief challenge.

The duo began the third day of a gruelling five day challenge on Wednesday during which, between them, they will attempt to sit on every one of the 90,000 seats inside Wembley Stadium.

Former rower Redgrave  won all of his medals whilst sitting on his backside, so such a challenge should have been right up his ally but having spent two minutes replicating what Shearer and Savage will do for 12 hours a day he admitted it was more difficult than he could have possibly imagined.

“It just goes to show you how difficult it is, it uses strange muscles,” said the man who won gold at consecutive Olympic games between 1984 and 2000.

“I used to sit down for my sport so you’d think this would suit me down to the ground, but I never moved sideways I always moved backwards.

“I’ve just done a two minute challenge,” he continued, “and after 60 seconds, I was absolutely exhausted.”

“I do top the list of people who’ve done the two minute challenge at the moment. There’s only myself and Graham Poll who’ve done it but at least I’ve beaten Graham Poll,” he added, with a smile.

Redgrave feels the biggest obstacle facing Shearer and Savage is the mental challenge of staying motivated.

With 25,000 seats still to go at the start of Wednesday, the former rower feels the two ex-footballers face a real battle over the coming days.

“The trick is to switch off and not really think about what you are doing,” he said, “Football is a high intensity explosive sport whereas this is more my domain of low intensity endurance.”

Shearer and Savage’s Battle of the Backsides challenge is all in aid of Sport Relief.

To support them in this brutal task, as well as to be in with the chance to win some amazing prizes, the public can enter a competition at sportrelief.com/backsides. Each competition entry costs £5, and there are some incredible prizes up for grabs including tickets to see England play at the 2014 FIFA World Cup in Brazil, two centre court tickets to Wimbledon 2nd round or tickets to One Direction on their UK tour. There’s a limited 90,000 entries available to represent the number of seats collectively sat on during the challenge.
 
Alan and Robbie are putting their bottoms on the line in the hope of raising a lifesaving sum of cash to help change the lives of vulnerable people in the UK and around the world. 
 
Fans can follow all the action from Wembley over the five days with regular updates on BBC Radio 5 live and bbc.co.uk/backsides.