Richard Hughes will ride Night Of Thunder in Saturday's Queen Elizabeth II Stakes at Ascot with stablemate Toronado going to the Breeders' Cup.
Toronado, trained by Richard Hannon, is the latest Group One winner to be ruled out of British Champions Day.
The Queen Anne Stakes victor will race instead in the Breeders' Cup Mile at Santa Anita in America on 1 November.
Hannon hopes Ryan Moore will be free to ride his other QEII Stakes contender Toormore at Ascot on Saturday.
|Harry Herbert, spokesman for owners Al Shaqab, on Toronado|
|"Due to the ground, we will bypass Ascot and head for the Breeders' Cup Mile instead. He loves fast ground and conditions at Ascot don't look like they will suit."|
Night Of Thunder beat Kingman and Australia to win a high-class 2000 Guineas at Newmarket in May.
But the Guineas second and third have been retired, adding to a list of top performers who will miss the big fixture at Ascot.
Kingston Hill, The Grey Gatsby and Rizeena are among those being rested until next year.
Top horses who will be running on Britain's richest raceday include Estimate, owned by the Queen, in the Long Distance Cup; 2000 Guineas winner Night Of Thunder in the Queen Elizabeth II Stakes and Champion Stakes contenders Cirrus Des Aigles, Free Eagle and Noble Mission.
Officials insist there is no prospect of Saturday's meeting being called off despite 42mm of rain falling in the 36 hours to Tuesday morning.
The going at the Surrey track is described as heavy, but the weather forecast predicts drier conditions as the week progresses.
|Qipco British Champions Day, Ascot, Saturday 18 October (all times BST)|
|13:45 Long Distance Cup (Group Two) two miles|
|14:20 Sprint Stakes (Group Two) six furlongs|
|14:55 Fillies & Mare Stakes (Group One) one-and-a-half miles|
|15:30 Queen Elizabeth II Stakes (Group One) one mile|
|16:05 Champion Stakes (Group One) one-and-a-quarter miles|