Two 10-year-old boys will swim, cycle and run to raise money for their young friend who suffers from a rare form of Muscular Dystrophy.
Max McKinlay and Tom Abbott will begin their triathlon on Sunday with a 200 metre swim at Wimbledon Leisure Centre.
They will then run 2.4 miles to Max’s home in Revelstoke Road, Wimbledon, before taking to two wheels for seven laps around Wimbledon Park.
The youngsters devised the triathlon event because they wanted to help Matthew Newnham, who goes to their school, Willington Independent Preparatory School in Worcester Road, Wimbledon, and who was diagnosed with Limb-girdle Muscular Dystrophy.
The genetic condition affects the voluntary muscles, mainly those around the hips and shoulders and there is no cure.
Although Matthew is very active and plays in goal for the school football team and bats in cricket matches, he will not be joining his friends for the event, but will be cheering from the sidelines.
Max's mother, Becky McKinlay, said: "I think it is wonderful they are doing this.
"I am incredibly proud of them that they created this idea.
"It is an incredible thing for two 10-year-olds to do."
The sporty youngsters will have to dodge people camping for Wimbledon tennis championship tickets in the park on Sunday.
The event on Sunday, June 29, will not take the form of a conventional triathlon, which is the swim first then the cycling then the running last, because of logistics.
Mrs McKinlay said they would like people to cheer them on.
They are hoping to raise £3,000 for Muscular Dystrophy Campaign which is researching treatments and a cure for the disease, and the boys already more than halfway to their target.
For details on the route and how to donate, visit the website.