Sydney superstar Isaac Heeney's Brownlow Medal hopes have taken a massive hit after he was unsuccessful in overturning a one-game suspension at the AFL tribunal.

Heeney will miss the Swans' clash with North Melbourne on Saturday and is out of the running for the AFL's highest individual honour. 

The 28-year-old was banned by the match review officer for striking St Kilda defender Jimmy Webster during the Swans' upset loss against the Saints on Sunday.

The forward-turned-midfielder was one of the favourites for the Brownlow until the sanction.

Heeney was taken out of Brownlow betting minutes after the incident, with Carlton captain Patrick Cripps installed as favourite, ahead of Collingwood's Nick Daicos.

The tribunal deliberated for about 40 minutes before agreeing with the one-game verdict.

"The swing of Heeney's arm was forceful and it was more than a swatting motion," AFL tribunal chair Jeff Gleeson said.

"We are not satisfied that he intended only to make contact with Webster's hands.

"This was an intentional strike resulting in injury."

Heeney went to break away from Webster and caught him across the face.

Webster was treated for a bloody nose on the field, but wasn't required to leave the ground and didn't need any ongoing medical attention.

Heeney told the tribunal the incident happened "extremely quickly" and he was intending to "swat" Webster's hand away so he could run towards the ball.

"It probably happens 50-100 times in some games," he said.

Heeney said that he had immediately realised what he had done and after he had marked and goaled, went to check on Webster.

St Kilda coach Ross Lyon also said post-match the incident was an accident, with no intent.

After Heeney's case, Adelaide were also up at the tribunal trying to downgrade the hefty four-game penalty playmaker Izak Rankine will serve.

The Crows accept Rankine will serve a ban, but they are arguing his bump on Brisbane Lions opponent Brandon Starcevich was careless, not intentional.

Following the collision, a Brisbane fan racially abused Rankine online and has since apologised publicly.

The Lions have cancelled his club membership and the AFL integrity department is investigating.

AFP