By Dave Woods
BBC Sport in Sydney
Australia forward Willie Mason has been suspended for one game and fined AU$5,000 for striking Great Britain prop Stuart Fielden on Saturday.
GB captain Jamie Peacock (left) took exception to Mason's punch
Mason pleaded not guilty to the charge following the incident in Britain's 23-12 Tri-Nations win in Sydney.
The Australian punched British prop Fielden and left him unconscious.
Mason had claimed provocation but a Rugby League International Federation disciplinary committee found that his response was "disproportionate".
The three-man panel consisted of Tri-Nations chairman Greg Woods, Australian nominee John Chalk and Britain's Nigel Wood.
I'm very surprised by tonight's result
Mason will now miss the Kangaroos' next Tri-Nations match against the Lions but will be eligible to play in the final.
"I'm really disappointed with the result," Mason said in a statement. "I honestly thought I was acting in self-defence.
"In light of previous incidents (in the Tri Nations) which have gone unpunished I'm very surprised by tonight's result.
"I will now devote myself to getting fit and play as well as I can in the final. I wish my team-mates the best of luck in the coming game.
"I feel like I've let them down but I can't wait for the final."
The charge was laid after the Great Britain team formally complained about the incident after the match.
"If I was a gambling man I would have said he'd get one game. But
self-defence - that was an interesting one," said Great Britain coach Brian Noble.
"The judiciary have dealt with it expediently and done the right thing, in my view, so we're certainly not whinging about that now.
"It's done and dusted now. He knows he's available for the final now, and we're not yet in it - so that's our focus."