With 100 days to go till the showpiece event, Australia know they face a battle to claim a place among the world's elite Olympic nations with the country set to send its smallest Games team in 20 years.
Around 400 athletes are expected to make the trip after the "Olyroos" failed to qualify for the football tournament for the first time since 1984. The women's team also missed out.
But chef-de-mission Nick Green said they will not go down without a fight.
"We know we are in for a tough tussle to claim a revered top-five spot with hosts and long-time rivals Britain, the strong European contingent headed by Germany and France, and the ever-present Japanese," said Green.
"But we know, as Aussies, we will never go down without a fight.
"Our athletes have to continue pushing in these final 100 days to give themselves the best chances of Olympic glory and ensure that we will hear Advance Australia Fair playing throughout the London venues."
Australia collected 14 golds at the last Games in Beijing and 46 medals overall, behind powerhouses China and the United States, as well as Russia and Britain.
In London they will again be relying on their swimmers to bolster the medal tally with swimming head coach Leigh Nugent targeting at least a dozen medals from their 44-strong squad led by 100m freestyle world champion James Magnussen.
But the team is without the experience of Ian Thorpe and Michael Klim, who missed selection, and is undergoing a major transition.
"The gap has closed on us... the US are the big challenge, they have dominated swimming for 100 years," Nugent said after the recent trials.
"There are other players who are making it tougher for us to stay in that number two position. The big movers are China and France."
A shift in power back to Britain at this month's track cycling world championships could also hurt Australia's chances of cracking the top five.
Britain won five of the 10 Olympic events at the Melbourne world titles a fortnight ago, while Australia took just three.
"Although the cycling may level itself out, we anticipate we can make some gains in other sports at the same time," said Green.
"Top five, absolutely. We don't need to re-adjust that. I think top five is the respectful and rightful position for Australia to aspire to."
The Olympics open on July 27.