Melbourne have suffered a major pre-finals blow, potentially losing key forward Jacob van Rooyen for the rest of the AFL season through suspension.

The Demons failed in their bid to have van Rooyen’s three-game ban for striking overturned or reduced.

It means he will miss the fifth-placed Demons’ final home-and-away game on Saturday against the Western Bulldogs, and that Melbourne will need to win two finals for him to play again this season.

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Van Rooyen is having a career-best season, kicking 42 goals in 22 games.

The Demons forward was charged with striking after he concussed Port Adelaide defender Aliir Aliir in a marking contest on Saturday night at Adelaide Oval. It was graded as severe impact, careless conduct and high impact.

After the 90-minute hearing, where van Rooyen testified that he was trying to mark the ball when he collected Aliir, the tribunal jury deliberated for nearly an hour before upholding the charge.

Melbourne will be without Jacob van Rooyen for their next three games due to a striking ban. Credit: AAP

Melbourne had argued van Rooyen’s attempt to mark the ball was not careless, but the tribunal rejected their case.

Tribunal chair Jeff Gleeson KC also turned down a bid from the Demons to have a biomechanist give evidence for van Rooyen.

“The swing of Van Rooyen’s left arm constituted the act of a strike. It was a forceful blow. It was not simply a trailing or leading arm that Aliir collided with,” Gleeson said in the verdict, adding the panel found it was careless.

“Van Rooyen was initially intending to mark the ball, but we find that shortly before impact, he ceased to intend to mark the ball. We say this despite van Rooyen’s evidence to the contrary.

“Even if it was van Rooyen’s sole objective at all times to contest the mark, we find that he did so in a way that failed to take reasonable care to avoid acts which could be reasonably foreseen to result in a reportable offence.

“Van Rooyen had time to move his right arm in response to seeing Aliir and he could have done so to some extent or sufficient extent with his left arm.”

The tribunal also found the impact was severe and said there was potential for further injury, such as a facial fracture.

AFL Tribunal’s full reason for keeping ban

We find that this was a strike.

The swing of Van Rooyen’s left arm, constituted the act of a strike. It was a forceful blow. It was not simply a trailing or leading arm that Aliir collided with.

We find that the strike was careless. Van Rooyen ran towards the ball with his eyes on the ball. Aliir came from the side and the vision shows that shortly prior to, at about the moment of leaving the ground, Van Rooyen’s eyes moved to Allir and the ball.

Van Rooyen was initially intending to mark the ball, but we find that shortly before impact, he ceased to intend to mark the ball.

We say this despite Van Rooyen’s evidence to the contrary.

The video evidence is quite inconsistent with Van Rooyen continuing to intend to mark the ball at all times prior to and at the moment of impact.

In particular, Van Rooyen does not have both arms outstretched or otherwise positioned consistent with his stated aim of taking a chest mark.

His left arm is well wide of his body and not shaping the mark and his right arm makes no observable movement to attempt to effect a chest mark.

Counsel for Van Rooyen submitted that the player was not challenged on his evidence that his sole objective was to mark the ball at all times. We disagree. It was put to Van Rooyen that his arms were not forward in a marking motion and that his right arm moved when he saw contact would occur.

Van Rooyen had sufficient opportunity to explain his position that he was intending to mark the ball, and would not reasonably have understood that he was not being challenged on this point.

This disposes of the argument on behalf of Van Royen that 18.5.3, the effect that this could not be a reportable offence because Van Rooyen’s sole objective was to contest the mark.

In any event, Law 22.2.1(b) makes clear that, notwithstanding any other provision in the laws, in all circumstances, a player owes a duty of care not to engage in conduct which will constitute a reportable offence being committed against that other player, to take reasonable care to avoid acts which can be reasonably foreseen to result in a reportable offence.

Even if it was Van Rooyen’s sole objective at all times to contest the mark, we find that he did so in a way that failed to take reasonable care to avoid acts which could be reasonably foreseen to result in a reportable offence.

Van Rooyen had time to move his right arm in response to seeing Aliir and he could have done so to some extent or sufficient extent with his left arm.

It was submitted on behalf of Van Rooyen that his fists were not clenched. It does not follow, however, that it remained his objective to mark the ball.

We are not assisted by the Berry matter, which was an attempt to spoil in different circumstances. Neither does the vision of Van Rooyen taking a chest mark in another match assist him. It shows his right arm moving to complete the mark in a manner that is not consistent with what the vision shows occurred in this matter.

We find that impact is severe. The blow was forceful and resulted in Aliir immediately falling limp to the ground, where he briefly remained motionless.

He left the field, played no further part in the game, and has suffered a concussion.

The potential for further injury, such as a facial fracture, was also present.