PORT Adelaide forward Lindsay Thomas has been hit with a three-game suspension for his bump on Geelong midfielder Scott Selwood that left the Cat concussed and in doubt to face Sydney on Saturday.

Earlier on Tuesday, Thomas accepted a one-match ban for striking Selwood's elder brother Joel moments after the initial clash, which was assessed as intentional conduct with low impact to the head, which means the 30-year-old will be out for the next four rounds.

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The rookie will be unavailable to face his former side North Melbourne, West Coast, Adelaide and Gold Coast.

Thomas ran past the football, which is allowed if it is within five metres, and collected Scott Selwood as he tried to win the ball. 

The Tribunal panel, consisting of Jason Johnson, Richard Loveridge and Shane Wakelin, deliberated for six minutes before coming to its decision.

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Both lawyers argued Thomas' penalty for striking Joel Selwood should be considered when determining a sanction. AFL Legal Counsel Nick Pane QC sought a four-match penalty for the Port forward while Thomas' advocate Ben Krupka argued for three games.

Krupka referred to the former Roo's age (30), his 206 career games, his status as a Port rookie and that anything more than a three-game ban "has the potential to be crushing" to Thomas' career.

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Port accepted the categorisation of severe impact but argued it was only just in that category, rather than high.

Two previous incidents were referred to: Greater Western Sydney forward Jeremy Cameron's bump that left Brisbane onballer Rhys Mathieson with a fractured cheekbone in the 2016 pre-season competition (graded as severe impact) and former Fremantle defender Zac Dawson's bump in July 2016, which was graded as high impact, that collected Sydney backman Jake Lloyd.

Krupka contended the impact of Thomas' hit lay somewhere between Cameron's and Dawson's.

Cameron received a four-game ban while Dawson copped three matches, up from two because of his bad record.

Geelong's medical report found Selwood was vomiting in the rooms after the game and had a headache, was expected to miss two days of training and was no certainty to face Sydney on Saturday afternoon.

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Pane QC pointed out the Tribunal had the discretion to consider Thomas' bad record, even if that option wasn't available to Match Review Officer Michael Christian.

Thomas' past record was brought into the hearing, consisting of his offences from both the AFL and VFL. However, Pane argued incidents which happened more than two years ago held less relevance.

The one incident Pane wanted to be considered came while Thomas was playing for Werribee last May, when he was rubbed out for five games in an act that saw Melbourne midfielder Corey Maynard hospitalised.

Krupka believed Thomas went as low as possible and chose a legitimate action in bumping. He had the incident shown frame-by-frame to show contact was made with Selwood's forearm first, before contact slipped up to the Cat's shoulder and then his head.