Wallabies back Adam Ashley-Cooper still likens it to a childhood dream but, in his case, it is one that comes true.

He is driving from the Central Coast to Norths club training on a Thursday night in late August, 2005, when his mobile rings. It is Wallabies coach Eddie Jones on the line.

Jones tells Ashley-Cooper he is needed in Perth as back-up to help the Wallabies prepare for their Tri Nations Test against South Africa at Subiaco Oval in two days' time.

Ashley-Cooper, now 31 and a veteran of 108 Tests, recalls his reply to Jones: "I said I was on my way to training. He said, 'You have to do a U-turn. Go and pack your stuff'."

Ashley-Cooper makes that turn. But his mind is spinning, especially after calling his mum to tell her of his change of plans and asking her to pack his bags to save time and give some chance of him making the flight to Perth.

"She thought I said I was going to church," he says. "I said, 'No … Perth', and she said, 'Why am I going to church in Perth?'"

Ashley-Cooper arrives at the airport shortly before his scheduled boarding time, makes the flight and settles in for the five-hour journey, unaware of what is to unfold two nights later.

Fast forward to game night … August 20, 2005.

The Wallabies have warmed up. Not selected and with no Wallabies uniform to wear, Ashley-Cooper is in civilian clothes, seated in the stands, tempted by the thought of a meat pie and a beer.

Suddenly a Wallabies official looks up and franticly calls him down to the Wallabies' locker room.

He is told Elton Flatley is a late scratching due to blurred vision, that reserve back Clyde Rathbone is in the starting side and he is needed on the bench.

Ashley-Cooper is given a playing kit, including a jersey without a number and, within minutes, is on the field singing Advance Australia Fair with the Wallabies.

But wait, there is more … when Rathbone comes off injured near the end of the Test that Australia lose 22-19, Ashley-Cooper is on for his first Test cap as the 800th Wallaby.

Ashley-Cooper, who on Saturday flew out with the Wallabies for his third World Cup via the US where Australia will play the US Eagles in Chicago on Saturday, is still amazed by his unorthodox Test debut.

"It's like that fairytale every kid dreams of," he says. "Every kid has had that dream of being at a stadium, or watching the Wallabies and, for some reason, the coach picks them from out in the crowd and asks them to train or play with the Wallabies."

Little wonder Ashley-Cooper also entertains the idea of a fairytale end to his Test career, saying that, as it "started with a fairytale … it's going to end with a fairytale".

It remains to be seen if Ashley-Cooper's adieu to Test rugby will be the World Cup, after which he will join French club Bordeaux.

Under Australian Rugby Union law, because he has more than 60 Test caps, he will still be eligible to play for Australia.

But as for the World Cup, Ashley-Cooper says it is "my last hurrah".

So when will that "last hurrah" be heard at the World Cup in England?

With a broad grin, Ashley-Cooper replies: "If you look at the [Wallabies'] history and how we are tracking – or how I am tracking – it was a quarter final in '07 and a semi-final in 2011.

"It's going to be a final in 2015. I'm all about the omens …"