The two stars were highlighting a Sport Relief project aimed to improve young people's opportunities in a particularly deprived inner city area
Sport relief have granted Â£5000 to 'project ReStart' in Ely and Caerau.
ReStart is a bus-based mobile youth club which uses sport to bring disadvantaged young people together in a bid to ease tensions and avoid gang-related conflict, will help to get young people involved in a range of activities, including rugby.
The ReStart bus, part of the Safety Cardiff charity, was donated to the project by Cardiff Bus two years ago and is designed to get teenagers of the streets of Caerau and Ely. As well as carrying sporting equipment, the bus is also equipped with computers, a PlayStation, turntables for budding DJ's and a cafe
Since it started Cardiff Bus said it has seen a 30% decline in the number of attacks on buses and vandalism.
Jonathan Davies said, "All over the place kids are hanging around on street corners, bored with nothing to do with their time.
"They start stealing this and get into vandalism, then something like this comes along and picks them up and brings them in."
And Matt added, "I've been very impressed with the set-up here - you'd be a fool not to be impressed.
"The youngsters I've seen are genuinely proud to be hanging out here, doing things they may not have the opportunity to do at home."
Anna Skeels, ReStart project manager, said, "It's fantastic when role models such as Matt Dawson and Jonathan Davies take such an interest in the work we're doing.
"These visits not only have a profound effect on the young people here on the day but also help build respect in the community for ReStart, so encouraging more young people to participate."
Sport Relief, a Comic Relief and BBC initiative, last year raised more than Â£14m to support projects in the UK and abroad. It will return this year in July with the Sport Relief Mile.
For more information visit www.sportrelief.com