James McDonald is expected to make an immediate impact at his first Cox Plate meeting aboard It's A Dundeel, favourite for one of the main support races.

But a victory in the feature event is not out of the question for the star young jockey who will have his first Cox Plate ride on the Mike Moroney-trained Group One winner Glass Harmonium.

"It's probably the race in the world I'd love to win, the Cox Plate, so to get the chance to ride in one is going to be great and hopefully we'll go well," McDonald said.

McDonald got his first look at Moonee Valley when he rode at Tuesday morning's Breakfast with the Best and put Spring Champion Stakes winner It's A Dundeel through his paces.

It's A Dundeel was later confirmed as a starter in the Group Two Mitchelton Wines Vase (2040m) on his way to the Victoria Derby (2500m) on Saturday week for which he is a raging favourite.

The Murray Baker-trained colt, who defeated Proisir in the Spring Champion to maintain his unbeaten record, is 32 handicapper rating points above his nearest rival in the Moonee Valley race but meets them all at level weights.

After partnering the three-year-old in work this week, McDonald fired an ominous warning heading towards Saturday's race and also the Victoria Derby.

"I think the horse is going as well as ever and feels, in his action, the best he's ever felt," McDonald said.

"If anything he's come on since that Spring Champion. That might sound funny, but he's feeling great."

Baker agonised over running It's A Dundeel on Saturday or heading straight into the Derby.

McDonald would have been comfortable with either decision.

But running at Moonee Valley gives the colt a chance to race in the Melbourne direction for the first time before tackling his major goal of the Derby.

McDonald said It's A Dundeel was just out "to have a look around" when he went to Moonee Valley earlier in the week.

"It was just to get familiar with the surroundings," he said.

"He did that really well. He was on the wrong leg down the back straight and really switched on when the speed quickened up.

"I was really happy with his work. He's feeling great and there's no worries going into Saturday."