In the moments after Voodoo Lad's recent last-to-first Moonee Valley win, a stunned Chris Parnham was glowing in his praise of the in-form gelding.

The 19-year-old suggested Voodoo Lad was up to Group One standard after his fast-finishing Listed win and on Saturday the horse gets the chance to prove it in the Sir Rupert Clarke Stakes at Caulfield.

Like Voodoo Lad, his jockey will be chasing a first Group One success.

"He was outstanding at Moonee Valley," Parnham said.

"Obviously he's got to take the next step to Group One company, but it's probably not a genuine Group One race. It's probably a Group Two field.

"If he can produce a similar run to Moonee Valley, I think he'll be very hard to beat.

"I have never had a horse let down with me like that. I haven't ridden a lot of good horses, and I'm not saying he's the best horse I've ridden, but that last furlong of the race at Moonee Valley was electrifying."

Parnham is unbeaten in three races on Voodoo Lad and partnered him in a jump-out at Casterton on Tuesday.

While he said the gelding didn't set the world on fire, he said he wasn't too worried.

"I think he's a race day horse and I'm really looking forward to Saturday," he said.

Voodoo Lad is prepared by premier Melbourne trainer Darren Weir who has won the Rupert Clarke with Trust In A Gust and Stratum Star in the past two years.

The gelding is the TAB's $5 second favourite behind the Chris Waller-trained Counterattack at $3.50.

Parnham's best Group One finish so far is a second on Smokin' Joey in the 2015 Futurity Stakes.

His rides on Saturday also include Leotie in the Thousand Guineas Prelude.

He chose to stick with the Henry Dwuer-trained filly over West Australian Whispering Brook who he rode for the first time to a close second at Moonee Valley three weeks ago.

"It was a pretty hard decision but I've ridden Leotie all preparation and she's shown a lot of promise," he said.

"I've been really looking forward to riding her in these races.

"Whispering Brook was pretty impressive the other day but I just thought Leotie might just have a bit more brilliance. But I could be wrong.

"If I got off Leotie and it won, I'd feel worse than if I got off Whispering Brook and it won, just because I've been with Leotie all the way through."