Aidan O'Brien will not run any horses against Enable in the Prix de l'Arc de Triomphe at Longchamp on Sunday due to them testing positive for a banned substance.

All of the Ballydoyle runners been withdrawn from the race after positive urine samples indicated the presence of a banned substance from contaminated feed.

Announcement on tomorrow’s runners pic.twitter.com/vG1BOPeHvr

— Ballydoyle Racing (@Ballydoyle) October 3, 2020

Japan, Sovereign, Mogul and Serpentine were set to run against Enable at ParisLongchamp on Sunday, as John Gosden’s mare bids to win the great race for an unprecedented third time. Stablemate Stradivarius will now be the mare's main danger in a field of eleven runners, while the wait goes on for O'Brien to add to his Arc tally of two.

None of the quartet will, however, take part after it emerged late on Saturday evening that they have tested positive for a banned substance, believed to be zilpaterol — potentially from batches of feed supplied by Gain Equine Nutrition.

On Friday, the supplier confirmed that it is “investigating the potential presence of a contaminant in some batches of our equine feed range”.

The absence of O’Brien’s runners was announced via a Tweet on the official account of O’Brien’s Ballydoyle yard.

It read: “Unfortunately the results of the urine samples taken from the horses yesterday have come back positive from the French laboratory.

“There is a possibility that the contaminant may have left their system by the time of racing tomorrow — however we have no guarantee of this, and in order to protect the integrity of racing we have decided to withdraw all our horses from racing tomorrow.

“Joseph and Donnacha O’Brien will do likewise.”

O’Brien’s two sons each had leading Group One contenders due to race on Sunday.

Donnacha was looking to win a fourth Group One in his rookie season with Fancy Blue, who was declared in the Prix de l’Opera. While older brother Joseph had Pretty Gorgeous in the Qatar Prix Marcel Boussac.