The duo, who were conspicuous in New Zealand Football branded clothing and also brandished tablets and notepads, were immediately asked to leave.
"There were only a few spectators there and they were mostly Serbian fans," said one onlooker. "The Serbian team seemed quite relaxed about it but the American guy was quite aggressive...maybe he thought people were spying. People were already in their seats but he was trying to march them out. The New Zealand guys were quite obvious though, turning up in their gear and with tablets. They were quickly evicted."
The match was played outside the official pre-tournament Fifa window, which started on Monday. It was one of a number of games played on Sunday, including New Zealand versus Austria (Bays City Stadium), Uruguay versus Ukraine (Mt Smart Stadium) and Panama vs Uzbekistan (Endeavour Park, Porirua). All of the above matches were 'open', except for the USA-Serbia game.
A few hardy spectators circumvented the American 'ban', watching the game from a public footpath overlooking Trusts Stadium. The USA officials threatened to call the police unless the punters withdrew, and also said that their tickets for any tournament matches would be confiscated.
A Fifa spokesperson said it was the match was a private arrangement between the USA and Serbia and not controlled or arranged by Fifa. Attempts to gain comment from the USA team were unsuccessful.
The USA's first game is against Myanmar in Whangarei tomorrow (4pm), preceded by the New Zealand vs Ukraine clash at North Harbour Stadium to open the tournament (1pm).