Cranbourne trainer Clinton McDonald's pricey conviction about the prospects of Rosberg could be about to be vindicated.

The Group 1-winning trainer helped prepare the Deep Field colt for last year's Inglis Ready2Race Sale in Sydney and, rather than let him head to another stable, he bought him back for $750,000, significantly more than his $260,000 Inglis Easter yearling sale price.

The unraced colt, who just turned three, won a Cranbourne jump out by 10 lengths on Monday and his trainer has some lofty targets for the valuable colt.

"He's one of these colts that we've known for a long time that he's got good ability and he keeps jumping each hurdle or every task that we ask of him," McDonald told Racing.com.

"At this stage, he's trucking along well. He'll probably have one more trial and then be ready to go to the races. There are two options for him; he can go on the 27th to Sandown Hillside for a 1000-metre three-year-old maiden or we can step him off in the McNeil, 1200m on the 30th," he said.

"We'll get through his next trial first, but we think he's a Group colt. Then we've got options as to whether we go to a Golden Rose or whether we set him for the Coolmore."

Rosberg was bred by SF Bloodstock and Blake Sandblom.