Prime Minister Kevin Rudd has told Australia's Olympic athletes the entire nation is behind them and will go "through the roof" when the first medal is won in Beijing.

Rudd rallied the Australian athletes at the official team reception in China ahead of Friday night's Olympic opening ceremony.

"Today the nation honours you for your great achievement in making it into this Australian Olympic team," he said.

"And today the nation has one simple message for you and this is: `on every day in every event at every turn the entire Australian nation is behind you, every man, woman and child'.

"'As you march into the stadium tomorrow night, know this: the eyes of the all Australians are on you, from Torres Strait to Tassie, from Cottesloe to Coogee, from both city and bush, from our first Australians to those who have just become Australians'.

"'We are all behind these great Olympians of Australia, 100 per cent of the way'."

Rudd drew on the experience of an Olympic rower to motivate several hundred athletes and officials at Thursday night's reception.

He said the rower explained that being an Olympian meant drawing deep on the positive achievements of the entire team.

The prime minister presented flagbearer James Tomkins with the Australian flag he will carry as he leads the athletes onto the National Stadium in Beijing.

Noting Tomkins' great height, he said it reminded him of Caesar sending his tallest centurion into battle.

"It's great to see (AOC president John) Coatesy's a great student of Roman history," he said.

But he ended his pep-talk by starting three cheers for the team and then declaring: "Go get `em, Australia," which prompted an outbreak of Aussie, Aussie, Aussie.

Also lending their support to the athletes was Crown Princess Mary and Crown Prince Frederik of Denmark, former prime minister John Howard, Sports Minister Kate Ellis and Trade Minister Simon Crean.

Former Tasmanian Princess Mary, who met Prince Frederick at the Sydney Olympics, said the night had a warm atmosphere.

"It's quite overwhelming and all these people are coming up and are so excited to meet us," she said.

"It's a lovely and relaxed atmosphere to take a moment to chat with some of the Australian athletes and hear about their expectations and how they see the city and the facilities, and I'm actually looking forward to competition."

However, Princess Mary said her allegiance was not divided.

"My allegiance is with Denmark, but as Denmark and Australia don't compete so often, I also follow the Australian athletes as closely as I possibly can."

Australia pop star Natalie Bassingthwaite sang the Australian anthem to the athletes.