WEST Coast star Nic Naitanui will miss Saturday's clash against Greater Western Sydney after his challenge against a one-match suspension for a dangerous tackle failed at a marathon hearing of the AFL Tribunal on Tuesday night.

Naitanui tackled Port Adelaide's Karl Amon from behind midway through the final quarter of the Eagles' 42-point victory at Optus Stadium last Saturday and, as the Power player fell to the ground, landed on top of him.

After a hearing that ran for nearly two hours, jury members Richard Loveridge, David Neitz and Shane Wakelin deliberated for 15 minutes before upholding Naitanui's suspension.

The Eagles have the right of appeal and it's understood they will discuss that option with Naitanui's lawyer, David Grace QC, on Thursday morning.

AS IT HAPPENED Recap Wednesday night's Tribunal hearing

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Naitanui said after the hearing he was "a little bit dumbfounded" by Wednesday night's ruling.

"I don't think I feel like I need to change anything. There was no malice in it. There was no aggression," Naitanui said.

"It was just a tackle, I guess, and that's part of our game. It's been part of our game since day one.

"If I was seeking to go out and hurt someone, then I'd cop what I needed to and I wouldn't be as disappointed.

"But because it was just an act that I've done for the last 10 years of my career, I was left a little bit dumbfounded to a degree."

Earlier, Naitanui had given evidence via video link from Perth, saying his intention had been to tackle Amon by rolling him on to his left side, so that he finished underneath the Port midfielder.

The Eagles ruckman said he was unable to do this because Amon braced himself with his left leg, but argued he had still been able to turn himself so that he only landed on Amon with the right side of his body.

Port Adelaide doctor Mark Fisher testified by conference call that Amon had suffered a delayed mild concussion and was satisfied "beyond reasonable doubt" that Naitanui's tackle had caused this.

Naitanui (l) chats to Power ruckman Paddy Ryder after Saturday's game. Picture: AFL Photos

Naitanui's lawyer Grace pointed to a number of other incidents earlier in the game in which Amon's head hit the ground – including a tackle from Andrew Gaff and a tangle with Jackson Nelson – and said these could have contributed to his concussion.

Grace also noted Fisher's evidence that Amon had not reported concussion symptoms when he came to the bench two or three minutes after Naitanui's tackle, only when he had come off again late in the match. 

Grace also argued that even if Naitanui's tackle was found to be careless, the force of it was low rather than the medium grading it was given by Match Review Officer Michael Christian.

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The AFL's legal counsel, Jeff Gleeson, accepted there was no malice in Naitanui's tackle, but argued that the Eagle, at 110kg, hadn't exercised his duty of care to a player he outweighed by about 30kg. 

Gleeson said Naitanui had used excessive force by propelling himself forward with his last step and driving his right shoulder into Amon's back.

Gleeson said the force Naitanui approached Amon with meant it was "an inevitable consequence" that Amon's head was going to make "vigorous contact with the turf".

Meanwhile, Amon remains in doubt for Port's game against Adelaide on Saturday. 

Fisher said the midfielder had resumed light training on Wednesday, but would have to pass a concussion test on Friday to play against the Crows.

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