Olympic showjumping champion Cian O'Connor will be bidding to save his gold medal tomorrow when he goes before the Fédération Equestre Internationale's (FEI) judicial committee at a special hearing in Zurich.
The 25-year-old Co Kildare rider will have the opportunity to explain the presence of two banned substances in his horse, Waterford Crystal, and has lined up a high-powered legal team to defend his case.
According to judicial committee chairman Ken Lalo, the hearing is expected to last well into tomorrow evening and may have to be adjourned until Monday.
"Usually our hearings end at five or six o'clock," Mr Lalo said, "but it could go on until nine o'clock and there's always a possibility that it would run over two days."
Tomorrow's hearing, which is scheduled to start at 9.30am, will be held in the Unique Convention Centre adjoining Zurich airport. It will not be open to the press but a statement on the decision will be issued immediately afterwards.
Two human drugs, Fluphenazine and Zuclopenthixol, were found in a urine sample taken from the horse on the night of O'Connor's victory in Athens, where the showjumper earned the only Irish medal at the 2004 Olympics.
Testing on the sample was carried out at the FEI central testing laboratory in Paris, and O'Connor was informed of the findings by the international governing body on October 7th.
The rider issued a statement protesting his innocence the following day.
Two days later he announced that another of his horses, ABC Landliebe, had tested positive for sedatives in Rome at the end of May last year.
O'Connor requested confirmatory analysis on Waterford Crystal's B urine sample.
But this sample was stolen in the driveway of the Horseracing Forensic Laboratory in Cambridgeshire on October 21st, having been sent to England from the Paris laboratory.
The theft was reported to Cambridgeshire police five days later, but the FEI made no official statement until November 1st.
The following day it was announced that files relating to ABC Landliebe had been taken in an apparent break-in at the Equestrian Federation of Ireland offices in Kill, Co Kildare. No one has been charged in relation to either incident.
With the disappearance of Waterford Crystal's B urine sample, the FEI had to rely on the B blood sample for confirmatory analysis.
Testing, which was carried out in a New York laboratory on November 8th in the presence of O'Connor's witnessing analyst, Dr Laurent Bigler, confirmed traces of Fluphenazine and Zuclopenthixol in the bloods and O'Connor announced the findings in a statement the following day.
The O'Connor team was given a deadline of December 2nd to furnish the FEI with explanations for the substances in the horse's system, but a series of extensions were granted and it was not until mid-January that O'Connor's submissions were lodged.
There was a further delay before the FEI submissions reached O'Connor's solicitor, Andrew Coonan, last month.