FREMANTLE captain Nat Fyfe has sent shockwaves through Brownlow Medal betting markets after a clash with Collingwood's Levi Greenwood that is sure to come under the scrutiny of the Match Review Officer.

Fyfe collided with Greenwood midway through the third quarter at the MCG on Sunday just after the Magpie tapped the ball to teammate Matthew Scharenberg.

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As Fyfe bumped Greenwood, he extended his left arm away from his body and appeared to catch him high with his forearm.

MRO Michael Christian typically frowns on bumps where players' arms come away from their bodies, but Fyfe will likely escape suspension given Greenwood got up quickly and played on.

With the impact of the clash likely to be graded as low and Fyfe's action almost certain to be deemed careless rather than intentional, he should escape with a fine, ensuring he remains eligible for the Brownlow.

It is also possible Christian could find there was insufficient force to justify any charge against Fyfe.

Fremantle coach Ross Lyon wasn't prepared to comment on the incident.

"I didn't see that. That's not just a throwaway line, but even if I did … unless you're going to pay my fine for the comments on the MRO I'm probably not prepared to comment."

Triple M radio reported soon after the incident that some betting agencies had suspended betting on the Brownlow Medal after Fyfe's clash with Greenwood, with the Freo skipper one of the early favourites for the game’s biggest individual honour.