Imaging has thrown off any effects from a brutal last-start scrimmage to earn his place in the Doncaster Mile with victory in the Ajax Stakes at Rosehill.

The former Irish horse's introduction to Australian racing was a brawl with Cascadian in the Liverpool City Cup two weeks ago which resulted in a suspension for Glen Boss.

Both lined up again in Saturday's Group Two race over 1500m and Cascadian again found himself in a spot of bother during the race.

But Imaging ($6.50) was in front and out of trouble and went on to beat his Chris Waller-trained stablemate Yulong Prince ($15) by a neck with Cascadian ($6) another two lengths third.

"That's what he was supposed to do first-up, but things went wrong," winning jockey James McDonald said.

"It just shows when a horse does get into a bit of a tussle, how much it takes it out of them.

"He dropped out last time but he wasn't dropping out today.

"I think he'll be a huge chance in a Doncaster. He's the real deal.

"He's obviously in that right camp for the Randwick mile."

Waller has won the Doncaster six times and could also have Saturday's Phar Lap Stakes winner Funstar in the mix.

"We are one step closer to the Doncaster," Waller said.

"He's in winning form and he's come out of that scrimmage well. It was good to see him find all the way to the line.

"I thought Yulong Prince was going to win for a moment. He will step up to 2000 metres next."

Liverpool City Cup winner Quackerjack started the $4.40 Ajax favourite with his jockey Josh Parr saying the track was against him.

"The ground just being so wet it took away the advantage he has bowling along at a strong tempo and building off that," Parr said.

"He is still in good shape for the Donny."

The win was McDonald's fourth on the day with the track going from soft to heavy after driving rain in Sydney.

Imaging firmed from $26 to $11 for the Doncaster Mile on April 4 with Japanese horse Mozu Ascot the $6 favourite.