Joost van der Westhuizen passed away yesterday at the age of 45
Van der Westhuizen won 89 Test caps for South Africa and was part of the team that won the 1995 Rugby World Cup.
But the former scrum-half had been battling motor neurone disease, also known as ALS, since 2011 and was confined to a wheelchair for his final years.
And now Dawson, a World Cup winner himself, has opened up on the last time he saw his fellow scrum-half at a charity dinner in London in 2015.
"Goodness only knows how many international rugby players were there," Dawson told the BBC.
"I sat next to Joost and his brother Peter, who has barely spent a moment from his side since he was confined to a wheelchair.
"Joost couldn't speak too clearly but understood every word spoken to him.
"As he muttered his answers, and Peter interpreted, Joost's eyes were bright blue with enthusiasm and energy for the stories we were recounting.
"I remember zoning out from the potential awkwardness of having to ask him to repeat what he had said as I could hear every word crystal clearly from how his expressive face altered and eyes widened.
"His smile as wide as his stride that devastated every opponent."
Dawson won 77 caps for England between 1995 and 2006, regularly finding himself up against Van der Westhuizen on the field.
But the Englishman admitted that his South African counterpart had almost been playing a different game in his heyday.
"Joost was one of the new breed of rugby players, not just a scrum-half," Dawson added.
"Traditionally, the position had been about kicking and passing from behind the forward pack.
"He tried playing the game at a very different pace, playing in different positions on the pitch – no one had really done that before.
"He was playing for South Africa in what would be an iconic era for the country, not just the sport.
"As one of the poster boys, he gave a huge amount to his country and his sport and millions of people in South Africa."