WEST Coast forward Willie Rioli has broken his silence, apologising to friends and family for his "mistake" that has cost him his 2019 season.

Rioli was provisionally suspended by ASADA on Thursday night after attempting to fudge an urine test on August 20.

Rioli has since fled the Eagles' touring party in Melbourne ahead of the club's semi-final against Geelong on Friday night and returned to family and friends in the Northern Territory.

He was joined by club official Ian Miller in departing Melbourne, with the long-time staffer well equipped in dealing with crisis as the Eagles' right-hand man for Ben Cousins in the early 2000s.

"Just want to thank all my real family & friends for all the love and support through this tough time!" Rioli said in a post on Facebook on Friday.

"Im so so sorry I had to put yous (sic) all through this! We will get through this!

"I'v gone through tougher times life support, depression, bullying an we've gotten through!

"Hopefully this lil mistake is a lesson to be learnt! This definitely doesn't define me as a person! I love yous all."

AFL chief executive Gillon McLachlan conceded on Friday that Rioli's season was over.

"Technically there are provisions for an expedited hearing but my understanding is (it won't be)," McLachlan said on 3AW on Friday when asked of the chances of a hearing before the Grand Final.

"The priority for West Coast and for us is Willie's mental health ... that's not something that's in contemplation.

"He has been provisionally suspended while ASADA continues their investigation and the case comes to a head.

"These things take some time and this is clearly something that's different from the standard ones so I'm sure it will take some time."

West Coast's season goes on the line against Geelong in Friday night's semi-final.

Speedster Jack Petruccelle has replaced Rioli as the only change from the side that defeated Essendon in last week's elimination final.