Tarzino's dominant Rosehill Guineas victory has convinced his jockey the colt can become the first three-year-old in more than two decades to complete the Victoria/Australian Derby double.

Since the Australian Derby was moved from the spring to the autumn only two horses - Dulcify (1978/79) and Mahogany (1993/94) - have claimed the two.

The Mick Price-trained Tarzino was a comfortable winner of Saturday's Guineas (2000m) at Rosehill and Craig Newitt believes he has the ATC Australian Derby (2400m) at Randwick on April 2 at his mercy.

"I know my horse's ability and I think without sounding a bit cocky, I think bad luck is probably the only thing that can beat him," Newitt told Melbourne radio station RSN.

Tarzino is the $1.90 Derby favourite ahead of in-form Godolphin colt Tally ($6) who has won four consecutive races this campaign including Friday night's Alister Clark Stakes at Moonee Valley.

In an ominous sign, Newitt believes Tarzino will improve again from the Rosehill Guineas.

"He's just starting to get up into his right distance range now," he said.

"You don't have to have real staying ability to be able to win Derbys but the one thing about this bloke, the further he goes the better he's going to get.

"I really look forward to the mile-and-a-half at Randwick on the big open spaces and hopefully he can do it again."

While Newitt and Price celebrated Guineas success on Saturday, things didn't go to script for the pair in the Golden Slipper with favourite Extreme Choice finishing eighth after missing the start.