When Craig Williams rode Adelaide youngster Fire Thunderbolt to victory at Flemington in the autumn he described him as the best two-year-old he'd ridden so far that season.

Williams is back on board at Caulfield on Saturday and Fire Thunderbolt's trainer Phillip Stokes is hoping the jockey will be similarly impressed with the spring three-year-old version.

Fire Thunderbolt runs in the Blue Sapphire Stakes (1200m), a race that represents "the deep end" to his trainer.

With the high-class filly Snitzerland and the Brisbane colt Sizzling engaged, the $250,000 Blue Sapphire is a support race on the Caulfield Guineas card that could easily be upgraded to black type.

"I've probably thrown him into the deep end," Stokes said.

"But at least we'll find out where we stand."

Fire Thunderbolt's impressive Flemington win followed an equally emphatic victory at Morphettville at his only other start.

In that race he beat his stablemate Maybe Discreet who last week showed she was up to spring class, winning the Group Two Edward Manifold Stakes at Flemington.

That win propelled Maybe Discreet into the market in next Wednesday's Group One Thousand Guineas at Caulfield.

"If Fire Thunderbolt could make the same sort of progression as her I'd be more than happy," Stokes said.

"But if he can't we'll just lower our sights a bit, there's plenty of races for him."

Snitzerland is a $1.85 favourite to make the Blue Sapphire her fourth win from as many starts this time in with Fire Thunderbolt at $17.