Australia day in Irish Derby
Winner of the Investec Derby at Epsom on his previous start, the colt followed in the hoofprints of his sire Galileo, who took both prizes in 2001, and his dam Ouija Board, who landed the Epsom and Irish Oaks in 2004.
Joseph O'Brien, riding his second Irish Derby winner, sat in third place as stablemates Kingfisher and Orchestra made the running, and he eased closer a quarter of a mile from home before leading a furlong out to score just as he liked by two and a half lengths.
The 1-8 favourite was eased down towards the end, while Kingfisher (25-1) ran on gamely to finish second and Orchestra held third as the O'Brien team filled the first three places.
Australia was sent off at a highly prohibitive price after the race was reduced to just five runners with the late defections of Epsom runner-up Kingston Hill and the winner's stablemate, Geoffrey Chaucer.
However, the expectant crowd got the result they had hoped for as the Ballydoyle inmate completed the Derby double in championship style.
O'Brien jnr said: "This is a very special horse, he was an armchair ride. He has a massive engine and we still haven't seen the best of this horse. I'd love to ride him at a mile and a quarter - I think that's going to be his thing on fast ground.
"His attitude and his pace sets him apart from the others. He's a great mover and he's so well balanced. When I walked him down to the barn and came back before the race for the parade, he'd have stayed asleep.
"The Irish Derby is one of the races you watch growing up. To be riding in the race is a dream and to win it is unbelievable."
O'Brien snr added: "He's got a lot of speed and so much class, it's incredible. He just relaxes in his races. Pace is his big thing, he just travels. It's very strange that he gets a mile and a half, but I would say he will shorten right up after that. I imagine he'll go back to a mile and a quarter now."
Asked about the possibility of Australia running in the Qipco Irish Champion Stakes at Leopardstown on September 13, he added: "I would say he was made for that race, and there's also the Juddmonte.
"I'd definitely think about the Arc, but you wouldn't want to run him in bad ground. He maybe might get a little rest now - the lads will decide that themselves."
Australia has been rated a special horse from his early days, as co-owner John Magnier explained.
He said: "It was very easy to spot Australia at the sales, being by Galileo out of such a famous mare. It was a no-brainer once he looked the part and, medically, he was OK.
"I was confident before the Irish Derby because I'd been listening to Aidan since he (Australia) was a two-year-old. You know Aidan doesn't do that (describe Australia as the best horse he has trained) in an arrogant way. He genuinely believes that and he just wanted to share it with people.
"Some days there would be Press people down there (Ballydoyle) for three and four hours at a time and I guess you wind up, you have to say something, so if he believed he was good, why not say it? It adds a bit of excitement and, of course, it puts 12st 7lb on the horse as it's a stick to beat yourself."