(CNN) -- While his jockey starved himself to make the weight limit, one of horse racing's new stars delivered the goods again despite piling on the pounds.
Australia, a three-year-old trained by champion Aidan O'Brien, romped to his fifth win in seven starts on Wednesday to add another notable victory to his resume.
The chestnut colt with an impeccable bloodline fueled speculation that he could become the next Frankel or Black Caviar by making light work of his return to action at the Juddmonte International Stakes at York.
He comfortably claimed the $750,000 first prize at the English venue's richest race of the season -- the same one where in 2012 Frankel won a record eighth consecutive Group One event.
It was Australia's first run since late June, when he won the Irish Derby to add to his victory at the Epsom Derby earlier that month.
"He was ready for a racecourse gallop, that was where he was at," said O'Brien told reporters.
"His weight rose alarmingly in the last three weeks but the lads at home were very happy. He was a lot of kilos up on his Derby run -- he was 15-20 kilos heavier -- and that's a lot of weight.
O'Brien's 21-year-old son Joseph -- who won the York race last year on Declaration of War -- had to drop considerable weight to continue his regular ride on Australia.
"I can't tell you the massive part Joseph plays," his father said. "He can do 8 stone 12 pounds (56 kg) but we don't like him doing it.
"We're quite happy for him to put overweight up when he does. In the big days we want Joseph to be on and this is one of them."
Australia's physical development since the prestigious Epsom win was remarkable, according to O'Brien.
"Joseph said that leaving the paddock in the Derby he felt like he was a two- or three-year-old, but today leaving he felt like a five-year-old," he said.
"There's such prize-money here and it's such a prestigious race that it's very hard to gallop him at a racecourse rather than bring him here."
Next up, the O'Briens will likely return to their homeland with Australia for the Irish Champion Stakes at Leopardstown on September 13, where the trainer has a leading seven career wins.
"The more we trained him when he came back, the heavier he got, and I'd imagine the run will leave him right," the 44-year-old said.
"I'll speak to the lads but hopefully he will go to Leopardstown. I'd love him to go there and get him back to Ireland."
Australia was sired by Galileo, who also won the Epsom Derby, Irish Derby and Irish Champion Stakes, while his mother is a two-time European Horse of the Year.
Galileo, meanwhile, sired the top-three finishers at the International Stakes, with The Grey Gatsby second ahead of Telescope.
Frankel, who retired unbeaten in 14 races in late 2012, was the world's top-ranked racehorse with a rating of 140 -- considered the best of all time.
Champion Australian sprinter Black Caviar then took over from Frankel at the top last year before retiring undefeated in 25 races.