Trainer James Cummings displays a sunny disposition when he predicts a weather-related shut-out for Sydney horses in recent weeks can finally lift on opening day of The Championships.

Cummings declared Prized Icon in prime form for Saturday's $2 million Australian Derby (2400m) at Randwick where he, among other Sydney-based trainers, will be trying to address an imbalance in races this autumn contested over 2000 metres or more.

The Derby falls into that category at 2400m and given recent form, New Zealand raider Gingernuts seems a logical $3.50 favourite with the TAB.

Gingernuts powered to victory in the Rosehill Guineas on March 18, leaving the gelding as one of eight interstate or New Zealand horses to score over middle distances this month.

Cranbourne-based Tavago started the trend on March 11 in the Sky High Stakes at Rosehill, one of a half-dozen Victorian horses to upstage the locals.

Jon Snow claimed another win for the New Zealanders in last weekend's Tulloch Stakes (2000m) on the heavy track.

Cummings trotted out those statistics when he explained why Sydney horses had failed to fire over 2000m, highlighting Gingernuts' superior fitness.

"A horse like the (Derby) favourite that won the Rosehill Guineas was able to come across here and gallop strongly on the sealed dirt, which we probably wouldn't do, on the Wednesday before he won the Guineas."

With Sydney's frequent downpours wreaking havoc with training regimes, visiting horses had the benefit of better preparations before tackling heavy ground.

Gingernuts won the New Zealand Derby (2400m) on a good track at Ellerslie and then dropped down in distance with ease for the Rosehill Guineas.

"Those horses that have come across are so fit," Cummings said.

"They definitely have the wood on us."

But Cummings believes Prized Icon now has the requisite lead-in form to add the Australian Derby to his Victoria Derby success in the spring.

The three-year-old colt ran a game three-length second to Jon Snow to give Cummings encouragement. It was a marked improvement on his sluggish 10th in the Guineas.

"He hated the ground at his last two starts at Rosehill but he really lifted to a new level on the weekend," Cummings said.

"Glyn Schofield (jockey) and I really believe that if we could get within three lengths of Jon Snow, who had the proper form going into the Tulloch, our horse could really improve out of sight."

Prized Icon, who jumps from barrier six, is on the fifth line of betting with the TAB as a $10 chance behind Gingernuts, Hawkes Racing-trained Randwick Guineas winner Inference ($4.40), the Murray Baker and Andrew Forsman-trained Jon Snow ($6) and Anaheim ($8), who is prepared by Trent Busuttin and Natalie Young.

Busuttin and Young won last year's Derby with Tavago who also came through the New Zealand Derby in which he was an unlucky sixth.