Champion jockey Damien Oliver has dragged himself from the depths of controversy to claim a Group One victory that meant more than most in the Thousand Guineas at Caulfield.

Oliver produced one of his most polished performances to land Commanding Jewel ($10) a 2-3/4 length winner on Wednesday, at the same time transforming her into the most valuable filly in Australia.

The two-time Melbourne Cup winning jockey has been mired in scandal since the weekend when allegations surfaced that he had bet $10,000 on a rival horse in a race in which he was riding two years ago.

The newspaper reports that stemmed from police investigations into race fixing have cost Oliver some prize spring mounts, including Green Moon in the Cox Plate and My Quest For Peace in Saturday's Caulfield Cup.

But among the trainers who stood by him was Leon Corstens who said he had no hesitation keeping Oliver on Commanding Jewel.

"He's the best rider in Australia," Corstens said.

"And he rode an unbelievable race."

It is far from the first time Oliver has crafted a major win while battling adversity.

In 2002 he scored one of the most emotional Melbourne Cup wins of all time on Media Puzzle a week after his older brother Jason, also a jockey, died from injuries suffered in a fall.

Oliver alluded to Media Puzzle's Melbourne Cup after Wednesday's Guineas, saying he had endured worse times than those he is enduring now, and had come through them.

"Everyone has tough times in their life," Oliver said.

"It's how you respond to them that matters."

He also recognised the loyalty of Corstens and Commanding Jewel's owners who stuck by him after he'd ridden the filly at her previous three starts.

"It's nice to have good people support you at times like this," he said.

"This is when you learn about people."

For Commanding Jewel's part-owner Brad Spicer, who selected the filly and paid $205,000 for her, the choice to retain Oliver was a simple one.

"There was no doubt in my mind that Damien would get the job done," Spicer said.

"He's the best."

Commanding Jewel ($10) gave Oliver his fifth Thousand Guineas win and his 95th Group One success when she beat Dear Demi ($11) by 2-3/4 lengths with Zydeco a nose away in third place.

She also increased her value many times over.

As well as being a brilliant winner, Commanding Jewel is a three-quarter sister to one of Australia's best racehorses and last year's Thousand Guineas winner, Atlantic Jewel, who broke down early in the spring before having a chance to improve her seven-from-seven record.

Oliver is yet to be charged by either the police or stewards over the allegations.