GEELONG captain Joel Selwood is free to play against Sydney on Saturday after the AFL Tribunal overturned his one-match suspension for striking Port Adelaide forward Lindsay Thomas.

Selwood told the Tribunal he had approached Thomas immediately after the Port forward bumped his brother Scott with the sole intention of telling him he had committed an "effing dog act".

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The Cats star conceded he had made contact with Thomas' head with his left fist, but only after the Power player pulled him down by his jumper.

Selwood also argued he had merely "brushed" Thomas, with the force insufficient to constitute a strike.

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The Tribunal jury members Jason Johnson, Richard Loveridge and Shane Wakelin deliberated for only five minutes before finding Selwood was not guilty of striking.

"I'm pleased to obviously get to plead my case tonight and have the opportunity to do it," Selwood said after the hour-long hearing.

"I'm really looking forward to taking on Sydney this weekend."

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Selwood was offered a one-match suspension by Match Review Officer Michael Christian after he grappled with Thomas during the second quarter of last Saturday night's game at Adelaide Oval. 

Selwood's action was assessed as intentional conduct with low impact to the head, but the Cats skipper elected to challenge the charge at the Tribunal. 

The incident occurred after Thomas ran past the ball and bumped Scott Selwood, a blow that concussed the Cat.

Joel Selwood told the Tribunal he did not know at the time that Scott was the Cat involved, nor that Thomas was the Power player who delivered the bump.

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He said he had walked over to Thomas at a measured pace, having heard an umpire's whistle signal a free kick for Geelong and conscious of not doing anything that would result in that being reversed. 

Selwood said he went to grab Thomas, but ended up by being grabbed by him. As the Port player lay on the ground, Selwood testified he was unexpectedly pulled off balance and down towards Thomas, which initiated the contact between them. 

The midfielder conceded he pushed Thomas with his left hand, but only to brace himself and try to maintain his balance.

Selwood's legal representative, Ben Ihle, said footage of Thomas on the bench just after the incident showed no signs of any marks on his face, while Port Adelaide's medical report stated he had required no treatment subsequently. 

The AFL's legal representative, Nick Pane QC, argued that Selwood grabbed a fistful of Thomas' jumper with his left hand and prior to impact intentionally took the opportunity to strike him.

Selwood flatly refuted this suggestion when cross-examined.