Suspended Australia winger Wendell Sailor has asked for the B sample of his failed drugs test to be analysed in an effort to clear his name.
Sailor's career could be ended if he receives a two-year ban
Sailor was suspended after his A sample tested positive for a banned substance, and would face a two-year ban if the B sample also shows a positive result.
Australian Sports Anti-Doping Authority (Asada) testers take two samples when drug testing players.
The results of the B sample test are set to be made available next week.
It is not known yet if Sailor's A sample tested positive for a recreational or a performance-enhancing drug.
"Wendell Sailor has informed us that he has formally requested Asada to test his B sample," the Australian Rugby Union (ARU) said in a statement.
"Asada has informed the ARU that the testing procedure will take place as soon as possible and that the test results are likely to be available next week."
Sailor's management team made no comment on the development.
"He could nominate either himself or a representative to be present when the bottle's opened and then it's tested by the lab," said Asada spokesman Simon Tidy.
The NSW Waratahs winger was stood down by his team the day before an important Super 14 matches against the Wellington Hurricanes on 13 May.
Sailor switched codes in a lucrative deal in 2002, and had four seasons with the Queensland Reds before moving to the Waratahs this year in a two-year deal.
He has already been fined and suspended for three matches this season over a drunken nightclub incident in Cape Town.
He was initially suspended for one match, fined A$500 and sent home from South Africa by the Waratahs.
But he had a suspended ARU two-match ban hanging over him from another indiscretion with the Wallabies in the same South African city last year, and was fined an extra A$3,500.