Commitment and strength secured him the Group One ride on Dissident but it is an affinity with the Randwick mile which could deliver Brenton Avdulla a Doncaster victory.

Avdulla has picked up the Doncaster Mile mount on the Peter Moody-trained three-year-old after pledging to get down to 51.5kg.

But it is more than an ability to ride light that swayed connections.

Jim Cassidy has partnered the colt in four autumn starts and his aggressive style was instrumental in lifting Dissident to a Randwick Guineas win.

With Cassidy riding Hawkspur for Chris Waller on Saturday, Avdulla appealed as a replacement.

"I committed to the weight and I think they wanted a vigorous rider on him," Avdulla said.

"There's not too many (riders) down in the weights that can do that so I was fortunate enough to get the ride."

Dissident toughed out a Guineas win over the Doncaster course and distance before a mediocre run in the Rosehill Guineas.

While his last-start sixth wasn't the result hoped for, Avdulla expects that middle-distance experience to hold the horse in good stead for the drop back to a tough Randwick Mile.

And he should know.

Avdulla has won three Group One races in Sydney, two of those over 1600m at Randwick - an Epsom Handicap and Flight Stakes on Secret Admirer.

His other was a Randwick Guineas victory on Ilovethiscity when the race was held at Warwick Farm.

"It's a track and distance I've always gotten on well with and I'm riding a horse I think is at the top of his game," Avdulla said.

"He deserves a crack, he's down in the weights and he's trained by a premier trainer."

Dissident is one of three Group One rides for Avdulla who will also partner Snitzerland in the TJ Smith Stakes (1200m) and favourite Believe Yourself in the Sires' Produce Stakes (1400m).