Gold Coast Suns ruckman Zac Smith has reportedly suffered a serious knee injury during a VFL practice match.

AFL Media's Michael Whiting reports that he could miss up to 12 weeks of action in a key blow to Gold Coast's ruck stocks.

The 31-year old departed the scratch match against Brisbane in the opening minutes and did not return.

It leaves the Suns with only co-captain Jarrod Witts and 20-year-old Academy graduate Matt Conroy in their available ruck stocks.

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Suns general management John Haines confirmed that Smith has suffered a PCL injury.

"Subsequent scans have confirmed some damage to his PCL," Haines told AFL Media. 

"Whilst disappointing for Zac, we know he will attack his rehab with 100 per cent commitment and look to return as quickly as possible."

Smith did not play a senior game for the Suns in 2020 after returning to the club following a four-year stint at Geelong.

The big man has made 115 AFL appearances since making his senior debut for Gold Coast in 2011.

The Suns face the Lions in their sole AAMI Community Series clash next Monday at Metricon Stadium before opening their season proper against West Coast at Optus Stadium on Sunday March 21.