Kevin Sinfield was granted Royal approval as he set off on his latest epic mission to raise funds to combat Motor Neurone Disease on Sunday with the Running Home for Christmas challenge.
Having already raised over £10m for four previous marathon feats, Sinfield is aiming to run more than 230 miles in seven days across all four parts of the United Kingdom.
It is his first fundraising quest since his friend and former Leeds team-mate Rob Burrow passed away at the age of 41 in June.
“I think it’s important we’re doing justice,” Sinfield said on BBC Breakfast. “I want to represent the Burrow family the best we can but also the MND family.
“They keep surprising us with some of the things they tell us and, through that, we get energy and want to push on even more.
“The response has been great over the last few years and the cities are actually inviting us there now.”
In a message on social media, the Prince of Wales told Sinfield: “What you and Rob have achieved has been incredible and it’s a very fitting tribute to his legacy, what you’re achieving again this week.
“I’m sure you’ll be running with him in your mind the whole way round.”
Sinfield was greeted by Merseyside football heroes Peter Reid and John Barnes before starting his first leg in the company of thousands of Father Christmases in the city’s annual Santa Dash.
After finishing the first leg in Wrexham, Sinfield will embark on a gruelling route from Gloucester to Hull on Monday.
Sinfield’s seven-day ultra run
Liverpool to Wrexham – 1 December
Gloucester to Bristol – 2 December
Belfast – 3 December
Glasgow – 4 December
Beverley to Hull – 5 December
Northampton to Leicester – 6 December
Old Trafford to Saddleworth – 7 December