Logician (right) wins the Great Voltigeur Stakes at York (Nigel French/PA)Logician will face seven rivals when he puts his unbeaten record on the line in the William Hill St Leger at Doncaster.

John Gosden’s colt instantly became a red-hot favourite for the world’s oldest Classic after claiming his fourth victory from as many starts in the Great Voltigeur at York last month.

The son of Frankel bids to provide his trainer with a fifth victory in the Town Moor showpiece on Saturday, and Frankie Dettori with a sixth.

Sir Dragonet is one of three runners for Aidan O'Brien in this year's St Leger
Sir Dragonet is one of three runners for Aidan O’Brien in this year’s St Leger (Martin Rickett/PA)

Aidan O’Brien already has six St Leger victories on his CV – and is bidding for a third straight success following the recent triumphs of Capri and Kew Gardens.

This year, the master of Ballydoyle runs Sir Dragonet – who finished a close-up fifth when favourite for the Investec Derby in early June – as well as recent Lonsdale Cup third Il Paradiso and rank outsider Western Australia.

Donnacha O’Brien flies in to ride Sir Dragonet, with Ryan Moore heading to Leopardstown – and the young jockey fancies his chances.

“I ride him in all his work, he’s absolutely flying at home and gives you a very good feel,” he told Racing TV.

“It’s always an unknown when they step up in trip, but he looks to have every chance of staying it – it’s an unknown for plenty in the race.

“I think Logician is a nice horse, but he’s going to have to improve to run to my level of form, being honest, and I think my lad is probably the one to beat.”

Sir Ron Priestley steps up in grade, having won five of his six starts this season for Mark Johnston, who also saddles Nayef Road.

Martyn Meade’s Geoffrey Freer Stakes winner Technician and Dashing Willoughby, from Andrew Balding’s yard, are the other hopefuls.