James McDonald's spring carnival campaign in Melbourne could provide a couple of firsts for the talented jockey.

But one appears more likely than the other.

McDonald is chasing a first Melbourne Group One win this spring, and he is also yet to taste success in a Group One Guineas race anywhere.

He gets the chance at achieving both at Caulfield on Saturday but with the presence of superstar Pierro in the Caulfield Guineas, that task will be difficult for his mount Ashokan.

McDonald's other Group One chance on Saturday is Glass Harmonium in the Toorak Handicap (1600m), and he is set to have a number of opportunities later in the carnival including It's A Dundeel who is favourite for the Victoria Derby.

Pierro is at $1.20 for the Caulfield Guineas.

McDonald fashioned an upset in last Saturday's Group One Spring Champion Stakes (2000m) at Randwick when It's A Dundeel defeated $1.28 favourite Proisir from the Gai Waterhouse stable.

"Maybe this one is a little bit different," McDonald said ahead of his ride on Ashokan.

"I had a feeling that he (It's A Dundeel) would upset him (Proisir) and as it turned out he did.

"Pierro, the way he's winning he's a superstar. It's going to make it hard for any of us to beat him but I'm not saying he can't get beaten. It is racing after all.

"He (Ashokan) has been thereabouts without winning but his form is OK."

The New Zealand hoop has been a regular visitor to Australia in the past couple of years but made a permanent move last month to set up a base in Sydney.

"I wanted to ride in the Guineas and I'd love to win a Guineas," he said.

"I haven't won a Group One Guineas before."

He says this spring carnival shapes as his best opportunity yet to win a Group One in Melbourne.

He has won two Group Ones in Sydney, one in Brisbane and one in Hong Kong as well as 10 in New Zealand.

Glass Harmonium ran fourth first-up in the Group One Sir Rupert Clarke Stakes and McDonald will ride him for the first time on Saturday.

"I'm looking forward to hopping on him actually. I think he's pretty well-weighted with 56.5 kilograms for a big horse like him."

Among McDonald's other rides is Temple Of Boom in the Group Two Schillaci Stakes (1000m).

McDonald won the Group One Galaxy at Randwick in April on the Tony Gollan-trained gelding and has also been aboard for two stakes wins at Flemington.