Doyen will face seven rivals in a high-class renewal of the Baileys Irish Champion Stakes at Leopardstown on Saturday.
The brilliant King George VI And Queen Elizabeth Diamond Stakes winner is even-money favourite with bookmakers following the final 48-hour declaration stage.
But he will undergo a stern examination of his credentials being dropped back in trip to 10 furlongs for the first time.
The strong home challenge is headed by Dermot Weld's Irish Derby hero Grey Swallow and the John Oxx-trained St James's Palace winner Azamour.
Aidan O'Brien relies on Powerscourt, first past the post in the Arlington Million on his latest outing but subsequently placed fourth after being found guilty of causing interference.
Rakti, impressive winner of the Prince Of Wales's Stakes but disappointing next time out in the Coral-Eclipse, represents Michael Jarvis, while David Elsworth saddles Juddmonte International runner-up Norse Dancer.
Millstreet will carry out pacemaking duties for Doyen and the field is completed by Mick Channon's Imperial Dancer.
Meanwhile, Soviet Song and Attraction will clash once again in the Coolmore Fusaichi Pegasus Matron Stakes at Leopardstown.
The James Fanshawe-trained Soviet Song inflicted the first ever defeat on dual Guineas heroine Attraction when she triumphed by two and a half lengths in the Falmouth Stakes in July.
The pair will face seven others in the Group One contest, including Sir Michael Stoute's Favourable Terms, Aidan O'Brien's Yesterday and the John Gosden-trained Phantom Wind.