|BBC Radio 5 live horse racing special|
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Jockey Joseph O'Brien says he expects dual Derby winner Australia to improve from his York win last time out in Saturday's Irish Champion Stakes.
"He won impressively at York and we were delighted about that, but we felt he would come on a couple of lengths from the race," O'Brien told BBC Sport.
O'Brien said 20-1 shot Al Kazeem could be a danger at Leopardstown.
The rider hinted that next month's Prix de l'Arc de Triomphe is not his next preferred target for Australia.
Australia is 5-1 second favourite with some bookmakers for the mile-and-a-half Longchamp race on 5 October, but is a lower price for the shorter Queen Elizabeth II Stakes or Champion Stakes at Ascot two weeks later.
"There's quite often soft ground for the Arc and that wouldn't be ideal. Then I suppose you look at the likes of British Champions Day (Ascot, 18 October) and I know the ground can be a bit slow there," said O'Brien, 21.
"I'd say the ground would have plenty of say in where he goes. We'll take it one step at a time and see what happens at the weekend.
"The Breeders' Cup (1 November, Santa Anita, LA) would have to be a possibility. I suppose he'd get his quick ground."
Australia was a close third in the one-mile 2,000 Guineas before winning the Derby over a mile and a half at Epsom.
He landed the Irish Derby before dropping back a quarter of a mile for the Juddmonte Stakes at York in August.
"A mile and a half is probably as far as he wants to go. We think he's better at a mile and a quarter and he'd have no problem with a mile," he said.
Asked if Saturday's distance of a mile-and-a-quarter (or 10 furlongs) was his optimum trip, the jockey replied: "I'd say 10 furlongs looks that way at the moment but if I had a choice of a mile or a mile-and-a-half, I'd say a mile. He did well to win the Derby, it was far enough for him.
"Whether he will go back to a mile after the weekend remains to be seen."
Aidan O'Brien has described Australia, a son of 2001 Derby winner Galileo and 2004 Oaks victor Ouija Board, as the best horse he has trained.
"He gives you a great feel, he's very relaxed, he has a great attitude, a great action. He's a very well balanced horse and has all the speed in the world," said Joseph.
"He's a jockey's dream as he relaxes and you can put him wherever you like in the race. He is a special horse. He won very well in York and we're hoping he can show us what he shows us at home."
|O'Brien's weighting game|
|The jockey, who is 6ft tall, wasted down to 8st 12lb, well below his preferred weight, to ride Australia at York. "I probably won't get to ride many horses like him, so it's not something you give up lightly," he said.|
Australia is rated 1-3 favourite for the Leopardstown race, for which a third of the 12 entries are trained in the UK.
Roger Charlton's Al Kazeem is back racing after a stud career was halted because of fertility issues, while Juddmonte runner-up The Grey Gatsby, Eclipse winner Mukhadram and fellow Group One scorer Noble Mission could also travel over.
"The Grey Gatsby and Al Kazeem are two massive threats," said O'Brien.
"Al Kazeem won the big one-and-a-quarter mile races through the early part of last season. The last day (at Windsor) he broke the track record and looks as though he is coming right back to himself.
"The Grey Gatsby ran a blinder at York and there are plenty of others in the race that are well entitled to take their chance."
O'Brien also said his mount Leading Light, the winner of the Gold Cup at Royal Ascot, has "a solid chance" in the Irish Leger at the Curragh on Sunday.
Rivals could include the Godolphin horse Encke - racing again after last year's six-month doping ban - who denied the O'Briens a Triple Crown when beating Camelot in the English St Leger at Doncaster two years ago.
"If he was to put in that kind of form again, you'd imagine he would be a formidable opponent," said O'Brien.
O'Brien will miss out on partnering Granddukeoftuscany, the stable's runner in Saturday's Leger at Doncaster, but said exact jockey arrangements had yet to be confirmed.