Champion jockey Glen Boss is sweating on a good barrier for Nostradamus to boost his chances of claiming a first Blue Diamond Stakes.

Melbourne's reigning premiership winner is yet to taste success in Victoria's only Group One event for two-year-olds but has a big opinion of Nostradamus, a colt trying to emulate his half-brother Star Witness who won the Blue Diamond (1200m) in 2010.

Nostradamus' hopes of victory in the Blue Diamond colts and geldings Prelude last start were cruelled by the widest barrier in a capacity field, and Boss is hoping for a better result at Tuesday's all-important draw for Saturday's $1 million event at Caulfield.

Trained by the Hawkes family partnership, Nostradamus won easily on debut at Flemington last month before running on to finish fourth in the Prelude won by Rubick.

"My horse ran extraordinary the other day. He jumped and over-reached and took his shoe straight off," Boss said.

"I was intending to ride him quiet but he got too far out of his ground because he just wouldn't go because of that.

"I thought he was very good and closed off well."

A good barrier draw for Nostradamus in the Blue Diamond would allow Boss to position the colt much closer to the speed than in the Prelude.

"I think for my bloke, because he's still learning, a good draw would be really helpful," Boss said.

"His first win was soft. He cantered in front and breezed to the line with no pressure.

"The other day things went wrong for him early with the shoe thing and then I drove him to get him into a spot and he got it wrong a bit for four of five strides. So he's still getting there."

Boss rates the Prelude winners Earthquake and Rubick, both unbeaten in two starts, as clearly the horses to beat.

"They are the two, no doubt," Boss said.

"But my horse, I think he's a very serious racehorse."

Nostradamus shares the fourth line of Diamond betting with unbeaten filly Nayeli.

A win by Nayeli or her stablemate Francesco would give trainer Gai Waterhouse her first Blue Diamond win.

Waterhouse has won every other Group One for juveniles in Australia but her best results in the Blue Diamond have been seconds to Wager (2004) and No Looking Back (2012).