"Unfortunately you can get caught up with all the romanticism of playing good football and creating chances, but generally it's the basics that cost you at this level and unfortunately it was a basic mistake that ultimately cost us."
It was a bad mistake, too.
Goalkeeper Michael O'Keefe, who played because of the groin injury to Jake Gleeson, flapped horribly at a corner and allowed Dmitry Baga to nod in simply at the far post right on the stroke of halftime.
It was a cruel blow for O'Keefe, who pulled off three tremendous saves later in the game, but an even bigger one for the team who have designs on making the quarter-finals. They had targeted a result against Belarus because they face a difficult assignment against Egypt on Monday morning before, as Nelsen put it, the "easier game" against Brazil.
They probably need four points to get out of their group and that would appear impossible now.
Egypt gave Brazil, one of the gold-medal favourites, a scare in their match today when they recovered from a 3-0 deficit to get back to 3-2 but a New Zealand side that started with nine senior internationals and seven first-choice All Whites will go into it with confidence.
The likes of Kosta Barbarouses, Marco Rojas, Chris Wood and Michael McGlinchey caused problems for Belarus with their sharp passing and movement but couldn't quite create enough to take advantage.
Wood's close-range header from a corner was just too close to the goalkeeper, Rojas' dipping shot was tipped over the bar and Wood skied his shot over the bar when played in on goal.
Belarus had the better of the second half as the Oly Whites tired, but couldn't consolidate their lead thanks to O'Keefe and the help of the woodwork.
Neil Emblen's side grew increasingly frustrated as the match slipped away and a combination of some lenient officiating and Belarus' volatile approach - their 1.88m brute of a striker set the tone when he took a dive in the first minute of the match that saw Smith receive a booking - created a feisty environment.
"We'll learn a lot from this game," Nelsen said. "We'll learn that, potentially, if we stay sharp in the mind and eliminate mistakes, we can get something from Egypt."
New Zealand 0 Belarus 1 (Dmitry Baga 45). HT: 0-1.
