Cian O'Connor has nominated the Horseracing Forensic Laboratory in Newmarket to carry out confirmatory analysis on the B sample from his Olympic gold medal horse.
O'Connor, who revealed 12 days ago that his Athens winner Waterford Crystal had tested positive to a "mild sedative", has also asked for a witnessing analyst to be present during the testing procedure.
The delay in sending the B sample for analysis was due to an administrative error when the International Equestrian Federation (FEI) sent O'Connor an extensive list of all the testing laboratories it uses worldwide instead of just the five reference laboratories used for testing B samples. O'Connor's nomination was not one of the reference laboratories.
"It was a misunderstanding," FEI secretary general Dr Bo Helander said yesterday.
"He was sent a list of all our labs, but these samples only get sent to reference labs. He got the whole list by mistake. It wasn't his fault."
The Horseracing Forensic Laboratory now has up to 21 days to test the B sample, but Dr Helander said yesterday that he would expect a result sooner.
The results will be passed on to the FEI's judicial committee, which is headed up by Israeli Dr Ken Lalo. Dublin lawyer Mr Philip O'Connor is also on the committee, along with deputy chairman Mr Erik Elstad from Norway and Belgian Mr Francis Michielsens.
If the B sample confirms the original positive test, O'Connor will then be given 10 days to explain the findings, but his legal team could well ask for an extension to prepare the defence, which will be presented to the judicial committee.