The faith Robbie Laing had in a ratbag sire has paid off with $4000 buy Polanski beating the blue bloods in the Victoria Derby.

Although Laing liked the pedigree of Rakti, his progeny had been less than impressive, but the trainer was determined to do things his way.

Polanski duly delivered under a confident ride from Hugh Bowman, who claimed his third Derby win in four years when the colt beat Sheikh Mohammed's Complacent in the blue riband.

"It is a fairytale," Laing said.

"Rakti left horrible horses and everyone gelded them.

"I was determined that I would get on and leave him a bull.

"He was crazy like the rest of them, but we persevered and he's a lovely horse now."

The trainer spent Derby eve poring over the Stud Book and his confidence soared when he traced Polanski back to Phar Lap.

Laing also believed Polanski would run the 2500 metres of the Derby but, like all the others, was unsure until the colt was tested at the distance.

Sent out the second favourite at $5.50, Polanski was midfield in the early stages, with outsider Throw The King setting the pace.

Bowman made his move on Polanski at the top of the straight and set off to gather in the leaders with Spring Champion Stakes winner Complacent ($7) chasing after missing the start.

But the son of English Derby winner Authorized couldn't make up the difference, with the margin a decisive three lengths.

Thunder Fantasy ($31), the least favoured of 2012 winning trainer Anthony Cummings' two runners, was another 1-1/4 lengths away third, with Spring Champion runner-up Criterion ($11) fourth.

Favourite Savvy Nature ($4), third in the Spring Champion, never fired a shot, beating just two runners home.

"How clinical was that," Laing said.

"Winning the Australian Cup with Roman Arch was fantastic, but this (Derby) is one of the real big ones.

"I'd heard about the Sydney form in the Spring Champion and studied it, but this horse had put on 10 kilos since his Norman Robinson win and was doing so well."

"He showed ability as a young horse. Every time we raised the bar he jumped it.

"I thought he was going to be closer, but I was very pleased to see him midfield in a fast-run Derby."

Bowman said the winner was strong to the line and had more to give.

"My gut feeling is that he is going to get better as he gets older," he said.

"I started to get confident from about the 1200 to 1300 (metres) when the pace improved significantly. I was able to get him into a beautiful gait."

Henry Plumptre, who heads Sheikh Mohammed's Darley Australia which races Complacent, was among the first to congratulate Laing on a job well done.

Cummings was pleased to see Thunder Fantasy run well, but rued Drago's outside barrier.

"Swap the barriers and it's a different story," he said.

"They are both nice horses, but the barriers determined where they finished."