Red cards to Tim Cahill in the opener against Germany and Harry Kewell in the match against Ghana has left the rest of the team to do the work of 11 men for much of this World Cup so far.

With only a three-day rest between games, the Socceroos could be forgiven for lacking a bit of energy.

But Emerton believes that the possibility of having 11 men on the park for 90 minutes is enough to lift he and his team-mates.

"We'll probably be better for it," Emerton said. "If we can play a game with 11 men, we will probably feel like we're running on air.

"I think physically the team's in very good shape, all the boys have worked exceptionally hard coming into this World Cup, so I can't see that being a problem."

On a psychological level, Emerton said that the Socceroos are more motivated than they ever have been having endured what could be said to be two unfortunate send-offs in the two games to date.

He added: "We know we haven't got the rub of the green, which is disappointing, we've played the majority of this World Cup with 10 men so far and both have been very, very harsh red cards.

"It's disappointing to lose Harry, but we get Tim back and after our good performance against Ghana, we should go into this match full of confidence."

Australia's possible progression depends on it winning against Serbia and either Ghana beating Germany, or Germany beating Ghana by a big enough margin for Australia to turn around a five-goal goal difference on the Africans.

But Emerton said the possibility that the Socceroos will need multiple goals in the match won't dramatically alter how they approach the game.

"We won't go gung-ho, we will still have a strategic plan and obviously, we'll be looking to win the game and hopefully Ghana can come up with an upset against Germany," he said.

"I've done the calculations plenty of times. We've all talked about the different scenarios. It's still possible.

"Germany could beat Ghana by three or four and that means we can beat the Serbs by one or two. It's still mathematically possible and we'll give it our best shot.

"If we get the win, we can walk away with our heads held high."