West Coast Eagles forward Willie Rioli has been provisionally suspended after being found to have substituted a urine sample.
The AFL was notified by ASADA on Wednesday after testing on the sample which was taken on August 20.
Rioli after arriving in Melbourne ahead of Friday's clash with Geelong was informed of the decision.
The maximum penalty if found guilty of the offence is four-years.
Jack Petrucelle was flown out of Perth bound for Melbourne to replace Rioli.