The six-year-old has finished third in the last two renewals of the midsummer showpiece and returns to England fresh from his third triumph in the Coronation Cup at Epsom – his sixth Group One success.
There is little doubt the son of Montjeu’s devastating acceleration is most potent on a sound surface.
O’Brien admits he would be concerned if conditions deteriorate during the week.
He said: “The quicker the ground the better for my horse.
“On good to firm, quick ground I’d be very happy.
“If it got much slower than good, I’d have a little worry.”
Ascot clerk of the course Chris Stickels is anticipating some rainfall at the track this week, but is unsure what volume to expect.St Nicholas Abbey is one of 11 horses in contention, with trainer Aidan O’Brien also having left in Chamonix and Ernest Hemingway.
Michael Stoute has supplemented King Edward VII Stakes winner Hillstar at a cost of £75,000 as he chases a record sixth King George triumph.
With Ryan Moore set to take the ride on the Royal Ascot hero, German raider Novellist will require a new jockey.
Moore steered the Wohler-trained four-year-old to Group One glory in last month’s Grand Prix de Saint-Cloud and was expected to keep the partnership intact.
Either William Buick or Johnny Murtagh will now come in for a plum spare ride.
Set to join Novellist on the cross-Channel journey is French superstar Cirrus Des Aigles.
Christophe Soumillon takes over from Olivier Peslier aboard Cirrus Des Aigles as the latter is retained to ride the Sheikh Abdullah Al Thani-owned Very Nice Name.
Very Nice Name won three times in Qatar earlier in the year and was third behind St Nicholas Abbey in the Dubai Sheema Classic at Meydan.
Roger Varian is anticipating a bold bid from Ektihaam, who won the Buckhounds Stakes over the course and distance before slipping up in the Hardwicke Stakes at the Royal meeting.
“He’s just had routine exercise this morning, he’s had a couple of canters, and he’ll do stronger work tomorrow,” said the Newmarket trainer.
The field is completed by Universal, Red Cadeaux and Irish Derby hero Trading Leather.
Mount Athos, Mukhadram, Mars, Hunter’s Light and Battle Of Marengo have all been scratched from the race.