Aidan O'Brien has taken the first tentative steps for a possible attempt on the Kentucky Derby by submitting a colossal 21-strong entry for this year's Triple Crown series in the US.

All the top names among the top Ballydoyle classic hopes are in the 21, including the double Group One winner, Minardi, the leading 2,000 Guineas fancy Hemingway and the top Epsom Derby hope Galileo.

O'Brien has yet to have a runner in the Kentucky Derby (May 5th) or in either of the other two legs of the American Triple Crown, the Preakness (May 19th) or the Belmont Stakes (June 9th).

However, he did come agonisingly close to landing the Breeders Cup Classic on dirt last November with Giant's Causeway, and that was at the Churchill Downs course where the Derby is run. Early nominations for the Triple Crown series closed yesterday.

Ireland has hit the Belmont scoresheet with Dermot Weld's Go And Go in 1990; and Sheikh Mohammed's Godolphin team have declared winning at Kentucky their number one ambition.

O'Brien said yesterday: "If we think a horse is suitable for the race, has done enough and if we're happy with him, then we will run in the Kentucky Derby. But a very good horse is needed."

O'Brien added: "It makes a lot more sense to enter these horses for the Triple Crown now. It cost $600 to enter each of them for the three races, whereas in a month or so it might cost up to $6,000 to enter for just one of the races."

Galileo, an impressive winner at Leopardstown on his only start, is already a 12 to 1 second favourite for the Epsom Derby. The similarly unbeaten Hemingway is 14 to 1 for that race and is also quoted at 10 to 1 for the 2,000 Guineas. Minardi is 7 to 1 third favourite for that mile classic.