Background
Nelsen was born in Christchurch.
Nelsen was born in Christchurch.
After attending Our Lady of the Assumption primary school and St Thomas of Canterbury College, he moved to the United States to play for Greensboro College in North Carolina in 1997. After spending two years at Greensboro and leading The Pride to the National Collegiate Athletic Association (NCAA) Division III championship match, only to lose to Ohio Wesleyan University, he transferred to Stanford University where he played his final two years of college soccer. He graduated with a bachelor's degree in political science.