One bookmaking firm said on Monday they were running scared of hot favourite Logician, who was trimmed to a top-priced 6-5 for the William Hill St Leger at Doncaster on Saturday.
Nicola McGeady, head of PR at Ladbrokes, said: "Although Aidan O’Brien has six of the 11 entries, it is Logician who we are running scared of. Ever since winning the Great Voltigeur Stakes, support for him has been constant."
The imposing John Gosden-trained colt was made 7-4 St Leger favourite after his impressive victory in the Great Voltigeur Stakes at York last month, but after the five-day forfeits for the final British Classic of the season he was a general even-money chance, including with Ladbrokes, to give his trainer a second Classic of the season.
Sir Dragonet, winner of the Chester Vase and top-priced 7-2 St Leger second-favourite, is one of six from Aidan O'Brien's Ballydoyle yard to remain in contention for the 1m6f contest.
Stablemate Il Paradiso, rated a 6-1 chance by the race sponsor after finishing third behind Stradivarius in the Lonsdale Cup, heads the remaining entries for O'Brien, who also has Barbados, Norway, South Pacific and Western Australia.
St Leger confirmations at the five-day stage
Barbados Aidan O'Brien
Dashing Willoughby Andrew Balding
Il Paradiso Aidan O'Brien
Logician John Gosden
Nayef Road Mark Johnston
Norway Aidan O'Brien
Sir Dragonet Aidan O'Brien
Sir Ron Priestley Mark Johnston
South Pacific Aidan O'Brien
Technician Martyn Meade
Western Australia Aidan O'Brien
The strongest domestic challenge looks likely to come from the improving Mark Johnston-trained Sir Ron Priestley and Team Valor's Technician, whose trainer Martyn Meade confirmed him on course for the race after a minor yard bug.
The Andrew Balding-trained Dashing Willoughby and Nayef Road, also trained by Johnston, complete the Classic line-up at the five-day stage.
The final Classic of the season is the centrepiece of Doncaster's four-day St Leger festival, which begins on Wednesday. Speaking on Monday, clerk of the course Roderick Duncan said: "We have declared on good to firm, and as of Monday morning we have had up to 2mm of rainfall, which was forecast.
"There is a risk of showers on Tuesday night and running into Wednesday morning, but after that we have a predominantly dry forecast for the rest of the week. I think we're going to need a fair amount of rain to make any significant difference to the ground."