Showing true Olympic spirit, Guor Marial received a round of applause at a press conference after telling his incredible story of beating all the odds to be able to compete in Sunday's showcase event.
The 28-year-old, from South Sudan, fled his country and has not seen his family for almost 20 years.
But he said they will walk 37 miles (60km) in the hot African sun to get to the nearest town with a TV to watch him compete.
Marial, who now lives in the USA and has dedicated his run to refugees worldwide and his own people in South Sudan, said he had a message for his family back home.
'I just want to tell them I love them so much and I'm here for them, the whole country will be with me here.
'Bringing awareness to the country and hope the young generation will see me and will be able to dream high for the years to come.'
Marial will run under the flag of the International Olympic Committee (IOC) because South Sudan, a new nation, does not have its own Olympic organisation.
Marial added: 'Growing up in the war it was dangerous and hard. It was about survival of the fittest. If you survived one day, OK, what's going to happen next day? Growing up there, I did not know the outside world.
'When I left the village and go to the city and came to Cairo and the US, the world kept opening and opening. There is other things, not just about killing each other.
'I feel fortunate to have that, to have that background, that's helped me with my running and my everyday life.
'I'm looking forward to the race. To run under the Olympic flag is a great feeling, a lot of people don't get that opportunity, to represent the five rings is the best - represent the whole world.'