Below is the timeline of Guor Marial's preparation and participation in the London 2012 Olympics.
- In the run-up to the Olympics it appeared as if Guor's lack of citizenship in any nation would prevent him from competing at London 2012.
- But after considerable media coverage and lobbying, on July 21 the International Olympic Committee decided that Guor could run as an independent athlete. The statement on the IOC's website said:
- "The EB also approved a request to allow marathon runner Guor Marial to compete in the London 2012 Games as an Independent Olympic Athlete (IOA) under the Olympic flag. Marial was born in what is now South Sudan, which does not currently have a recognised National Olympic Committee. The athlete, who does not hold a passport from any country, is a permanent resident (refugee status green card) of the United States but not a citizen. As such, he is unable to compete for the United States, South Sudan or Sudan. Marial qualified for the Games with an A Standard time on 2 October 2011."
- In an interview with the Huffington Post after the announcement Guor describes how he was willing to give up on the chance to compete at the Olympics, after he had turned down an offer to represent Sudan, from which South Sudan separated in July 2011.
- In these weeks he was conducting three to four interviews a day, even responding to interview requests at 2am and 5am local time in his home of Flagstaff, Arizona.
- Marial arrived in London too late to participate in the opening ceremony.