St Kilda forward Ahmed Saad faces a two-year suspension from the game after delivering an irregular sample within the last month.
The 23-year-old, who burst into senior football from the VFL in 2012, is understood to have inadvertently taken a banned substance and is currently being investigated by the league. It is not known whether more than one sample has been provided by Saad, nor whether he has delivered more than one positive sample.
St Kilda confirmed that it was Saad being investigated on Wednesday afternoon, and that the player was "surprised and disappointed to find himself in this position".
In a statement on St Kilda's website, the club said: "St Kilda Football Club can confirm that Ahmed Saad is the player under review by the AFL for an alleged breach of the AFL Anti-Doping Code.
"Ahmed is surprised and extremely disappointed to find himself in this position, after returning a positive sample to a substance alleged to be on the prohibited list in the AFL Anti-Doping Code.
"Further tests will be conducted on the substance in the near future.
"The product suspected is permitted for use out of competition but is not allowed to be used in competition.
"The club is bound by confidentiality under the AFL Anti-Doping code and as a consequence cannot make further comment at this time."
Saad is an AFL multicultural ambassador. He has not played in the Saints senior side for the past three weeks. He was dropped after St Kilda’s defeat against Fremantle in round 15 but played in the VFL last week.
Under anti-doping rules his sentence could be significantly reduced should he demonstrate he mistakenly ingested a banned drug or supplement under the no-fault clause in international doping regulations.
Fairfax Media understands Saad has claimed he took the substance unwittingly.
Although the AFL is understood to have accepted the player could have taken the banned substance in error, he still faces a significant suspension from the game.
If charged, the St Kilda player would face a specially convened AFL tribunal hearing, chaired by David Jones and including at least one anti-doping expert.
Doping authorities have the power to overrule any decision handed down if it is deemed to be inappropriate.
VFL player Matthew Clark was suspended for two years after the banned substance dimethylamylamine was detected in his system after a game in 2011.
The Frankston midfielder was originally suspended for nine months, but that term was extended after ASADA appealed against the leniency of the initial suspension. It was found that Clark had accepted a pre-match drink, nicknamed "Hemo-rage", from a teammate.
Clark has always maintained that he was assured by his teammate the product was permitted under the drug code.
Richmond's Justin Charles was the first AFL player to be suspended for taking banned drugs, in his case an anabolic steroid. He was suspended for 16 weeks.
Come back at 8:30pm for a live blog of Channel Seven's interview with Dean Robinson.