Nelsen will reportedly take over from Mariner, who has been under pressure at the club after they finished with the worst record in the league last season - they went winless in their last 14 games - and have yet to make the playoffs in their six-year history.
Nelsen has tried to water down speculation but QPR manager Harry Redknapp doesn't expect his skipper to stay. "He has been offered a job in America and I think there is every chance he might want to go,'' Redknapp told reporters after QPR's 1-1 FA Cup draw with West Brom.
Redknapp said it would be a blow to QPR but it would be an even bigger one to New Zealand's chances of qualifying for consecutive World Cups. He was a large reason why the All Whites went unbeaten in South Africa in 2010 and, even at his age, is still the best player in the squad.
His influence extends beyond what happens on the pitch and teammates gain confidence by just having him around. The All Whites are in the box seat to qualify for November's intercontinental playoff with the fourth-best team from North and Central America.