Last year's St Leger hero has had a truncated campaign, but showed he was coming back to form when fifth behind Enable in the Prix de l'Arc de Triomphe.
O'Brien has yet to finalise his team, but it could include Hydrangea, who might bid to repeat last year's victory in the Qipco British Champions Fillies & Mares Stakes.
However, this year's Leger winner Kew Gardens may be excused duty in the Qipco British Champions Long Distance Cup after he finished seventh in the Arc, on what his eighth start of a busy campaign.
"I'm not sure if Kew Gardens will go," said O'Brien.
"We will decide early in the week and just see how he is. You are never sure if he will get two miles.
"He won the St Leger, so there is every chance, but he has had a long season, so we will see. It will all depend on how he is during the week, then we will decide.
"We will see how Capri is, as he might go for the Champion and Flag Of Honour might be supplemented for the Long Distance race.
"Hydrangea might go back for the mares' race and Happily, who finished second at Newmarket, might go for the QEII."
No fairytale ending
O'Brien is keeping an eye on Just Wonderful ahead of a possible tilt at the Breeders' Cup Juvenile Fillies' Turf at Churchill Downs early next month.
"It is possible that Just Wonderful could head out to America, but we will just see again with her," said the Ballydoyle trainer.
"Fairyland won't be going to America. She is finished for the year."
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