Club: Blackburn Rovers
Nelsen made his New Zealand All Whites debut against Poland on June 19, 1999.
Although he has been selected to play on numerous occasions, Nelsen had not represented New Zealand between his last appearance in 2004 and 2008 due largely to a recurring hamstring injury.
Nelsen captained the New Zealand U-23 squad for their first appearance at the Olympic Games against China as one of three over-age players, alongside Simon Elliott and Chris Killen, although he was only available for the opening two matches as Blackburn had requested that he return in time to prepare for their opening Premier League game of the 2008–09 season against Everton.
He also captained the New Zealand National Football Team side as they qualified for the 2010 Football World Cup, beating Bahrain National Football Team in a two-legged playoff in November 2009.