Aidan O'Brien sends a four-strong team into battle for the Investec Derby at Epsom and Coral offer 33-1 that he saddles the first three home in the premier Classic.

Red-hot favourite Australia, Ryan Moore's mount Geoffrey Chaucer and Chester Vase winner Orchestra all hold solid claims and it would not be a complete surprise were those three to dominate. O'Brien also runs Kingfisher.

Coral are official betting partners for the meeting and expect turnover of upwards of £20 million on the big race.

However, despite the ground quickening up throughout Friday under beautiful sunshine, the possibility of heavy showers on Saturday meant likely conditions remained up in the air on the eve of the big race.

"The presence of Australia in this year's Derby will ensure turnover remains healthy, as for all those punters who want to be with the favourite, there will be plenty looking to oppose him," said Coral's David Stevens.

"The market leader has been easy to back all week, and his price could yet drift further, particularly if Epsom is hit by the thunderstorms forecasters are predicting."

O'Brien has never made any secret of the regard in which he holds Australia, hailing him as his best ever Flat horse.

The Ballydoyle handler said: "Australia is uncomplicated, relaxed and has speed - exactly what you want in a racehorse. He's very natural and takes no training. He has a great mind and settles very well."

Of his other runners O'Brien said: "I was very happy with the way Orchestra won at Chester. If anyone had seen him there, they'd have seen that he had a bit of a tummy on him, and he'll come on for that. Kingfisher won well at Chester and is very straightforward horse.

"Nothing went right for Geoffrey Chaucer in the Derrinstown at Leopardstown as it was a very messy race with a slow pace. Joseph (O'Brien) had to go up the inside from where he was drawn."