Marial, who competed in the men's marathon, was the only Olympic veteran among the three. He had fled the Second Sudanese Civil War in 1999 and settled in the United States in 2001, where he took up athletics in high school. He ran for Iowa State University during his college career and was selected as a member of the All-American team. At the 2012 Summer Olympics, he had finished 47th in a field of 105 competitors. He was slated to make South Sudan's debut at the 2015 World Championships in Athletics, but failed to appear for the event. In Rio, he finished 82nd in a field of 155 competitors with a season-best time of 2:22.45.