Collingwood big man Mason Cox has been ruled out of Friday night's clash with Port Adelaide due to injury.

Collingwood's injury-prone tall, Ben Reid, will come in for his first game of the season, with Cox unable to recover from an ankle injury after a collision with Michael Hurley on Anzac Day.

Pies coach Nathan Buckley said Reid has been spending some time in the ruck in the VFL, so the change is a like-for-like replacement.

"That ankle just hasn’t come up for us ... there’s a bit of swelling and bleeding there that hasn’t come down as much as we would have hoped," Buckley said.

In better news for the club, star forward Jamie Elliott will return after training strongly this week.

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