Richard Hannon has elected to saddle QEII winner Olympic Glory rather than Toronado in the Breeders' Cup Mile at Santa Anita next week.
The Everleigh trainer was spoilt for choice in the American showpiece with his Group One pair, although Toronado had looked the more likely to travel.
However, assistant trainer Richard Hannon junior told the stable's website: "Toronado worked at Lingfield on Tuesday morning, but, having had a break since the wind operation that he had after York, he clearly needs a bit more time, so we will put him away for next season, when the Breeders' Cup will be his ultimate target.
"It was always going to be one or the other, but Olympic Glory has come out of last week's QEII victory at Ascot better than we could have hoped, so he will be our representative in the Mile.
Sheikh Joaan (Al Thani) is keen to have runners at the meeting, and we will also be taking his Shamshon for the Juvenile Turf."
Aidan O'Brien, meanwhile, has suggested Magician will take in the Turf rather than his option of the Mile.
An impressive winner of both the Dee Stakes at Chester and the Irish 2000 Guineas, the son of Galileo has not been seen since a very disappointing effort in the St James's Palace at Royal Ascot, for which he had suffered an interrupted preparation.
"We left him in the mile and the mile-and-a-half races, and it's very possible he could go for the mile and a half," said O'Brien.
"He ran a mile and a quarter at Chester, where he travelled well and quickened up well, and he just went wrong before Ascot, and it was all a bit much to overcome.
"He's had a good break, a few days away, and we're happy with him. The faster ground, the better."
Were Magician to contest the Turf, traditionally one of the European squad's most profitable races, and one O'Brien has claimed with both St Nicholas Abbey and High Chaparral, he could face Irish Champion Stakes star The Fugue as well as Jeremy Noseda's Grandeur.
John Gosden's The Fugue is the ante-post favourite, and is fancied by British Horseracing Authority handicapper Phil Smith.
He said: "She has beaten the boys and gets a fillies' allowance, so she looks to be our best chance."
Another doubly entered from the Ballydoyle team is Cristoforo Colombo, who was fifth in the 2000 Guineas at Newmarket but has only won a minor event at Dundalk this season. He was seventh in a six-furlong event at the Curragh 10 days ago.
"He's in the Mile, that's the race we were thinking of running in," said O'Brien, who said the colt would be "a possible for the Turf Sprint" if he did not get into the Mile.
"It just didn't work for him last time, Joseph (O'Brien) said he's better than that. There's no doubt he wants fast ground."
Possible other European runners in the Mile are Flotilla and Mshawish for Mikel Delzangles.
