The New Zealand Oly-Whites will have to seek a clearance from Queen's Park Rangers to secure captain Ryan Nelsen's services if they achieve the impossible and beat Brazil to reach the Olympic Games semifinal.

Nelsen is due to leave with QPR for a 10-day training camp in Germany on Saturday (NZ Time).

But, if the Oly-Whites beat Brazil and finish above Belarus and Egypt in pool play, they would play a quarterfinal game on Sunday.

New Zealand coach Neil Emblen said he would "cross that bridge when we come to it''.

But he said he would "hope'' QPR manager Mark Hughes would see that Nelsen was getting good quality games at the Olympics. "The preparation he's getting here is really good for Ryan at this stage of his career''.

Meanwhile, the Oly-Whites received a pre-match boost for tomorrow morning's clash with Brazil in Newcastle when left back Ian Hogg was cleared to play.

Hogg and over-age player Nelsen, 34, are the only survivors from the Oly-Whites team that lost 5-0 to Brazil at the Beijing Olympics in 2008.

Emblen said Hogg had recovered from a knock to his knee which forced him to be substituted in Monday's 1-1 draw with Egypt in Manchester.  The Auckland City defender missed New Zealand's first training session in Newcastle through illness but he took a full part today.

All Whites goalkeeper Jake Gleeson is fit for selection after recovering from a groin injury but Emblen may elect to retain Michael O'Keeffe, who was outstanding against Egypt.

Brazil have already qualified top of the group after wins over Egypt (3-2) and Belarus (3-1).

Emblen knows the odds are stacked against his team in "probably the biggest David versus Goliath match-up of this tournament''. 

"On paper, we are worlds apart. Most of their players will be the core of the side at the 2014 World Cup.

"Their squad is worth $300 million and ours have eight amateur players.''

Brazil can call on Manchester United fullback Rafaele,  France-based defender and captain Thiago da Silva, AC Milan striker Alexandre Pato and midfielder Neymar, who is being targeted by Barcelona.

Coach Mano Menezes has delayed naming his team but is reported to be considering changes.

Emblen would not be surprised if Brazil decide to rest some key players but he suspects all 18 members of the Brazilian squad are world-class.  Any new faces would be keen to press for places in the starting lineup for the quarterfinals.  "It could work for us, or against us,'' Emblen said.

Brazil have scored six goals at the Olympics to the Oly-Whites' one, a Chris Wood strike against Egypt.   But Emblen said New Zealand had conceded two goals to Brazil's three "against the same sides''.

Emblen vowed to continue a positive approach but he said "as long as [the score] can stay 0-0 as long as possible'', the Oly-Whites might have a chance if "we can be dangerous at the set-piece''.

Wood's goal came from a Michael McGlinchey corner, headed on by centreback Tommy Smith.

Possible Oly-Whites starting lineup: Michael O'Keeffe, Adam Thomas, Ryan Nelsen (capt), Tommy Smith, Ian Hogg, Marco Rojas, Tim Payne, Michael McGlinchey, Kosta Barbarouses, Shane Smeltz, Chris Wood.

- © Fairfax NZ News