Godolphin trainer Mahmood Al Zarooni will stand before a disciplinary panel of the British Horseracing Authority on Thursday afternoon after samples taken from 11 of his horses were found to have contained traces of anabolic steroids.
Al Zarooni could lose his training licence in one of the most significant alleged doping scandals in recent racing history.
The 37-year-old has officially been charged with rule breaches related to prohibited substances, duty to keep medication records, and conduct prejudicial to racing.
The hearing will be held at 2:30pm at BHA headquarters in London.
Samples were taken earlier this month from 45 horses trained by Al Zarooni at Moulton Paddocks Stables, Newmarket.
Subsequent analysis revealed 11 of the samples contained ethylestranol and stanozolol, which are prohibited substances.
Al Zarooni is one of two British-based trainers responsible for the horses of powerful owners Godolphin, the brainchild of Dubai ruler Sheikh Mohammed.
Those horses who had tested positive have been suspended from racing for an indefinite period.
Certify, unbeaten in four career outings and winner of the Shadwell Stud Fillies' Mile at Newmarket in September, was one of the seven horses whose sample tested positive for ethylestranol.
She had been ante-post favourite through the winter months for the Guineas, and only recently lost that position to the Sir Henry Cecil-trained Hot Snap.
Ascot Gold Cup runner-up Opinion Poll was one of four horses testing positive for stanozolol.
The BHA said on Wednesday that information provided by Al Zarooni to investigating officers revealed that, in addition to the 11 horses which tested positive, a further four horses - Comitas, Sashiko, Vacationer and Tearless - were administered one of the two prohibited substances.
Those horses were under the care of the Newmarket trainer, but but had not been subjected to testing.