ADELAIDE has copped a massive blow ahead of the new season, with key forward Riley Thilthorpe to be out for up to three-and-a-half months after requiring knee surgery.

Thilthorpe went under the knife on Wednesday after suffering a torn lateral meniscus in his left knee during Saturday's AAMI Community Series win over West Coast.

He will spend the next six weeks in a knee brace and be sidelined for 12-14 weeks. It means he won't return until just before Adelaide's mid-season bye, at the earliest.

Thilthorpe had been a standout performer at West Lakes in his fourth pre-season and appeared primed for a breakout year after adding the size needed to take on key defenders and growing in confidence as a result. 

His absence means the Crows will have to rely on Taylor Walker and Darcy Fogarty to lead their tall forward line, while recruit Chris Burgess could also come into the frame. Burgess was the leading goalkicker in the past two VFL seasons before joining from Gold Coast in the off-season.

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"It's obviously very disappointing for Riley and the team, he's had a fantastic pre-season and had put in a lot of hard work to put himself in a strong position for the year ahead," Crows High Performance Manager Darren Burgess said.

"But now his focus shifts to his rehabilitation and Riley is very diligent when it comes to his training and preparation which will hold him in good stead.

"Given his age and that he is such a valuable, long-term player for us, we are taking a conservative view with his return to play and see him being a significant contributor for the second half of our season.

"After a period of rest at home, he will continue his upper body training at the club and will spend about six weeks in a knee brace before progressing to on-legs training and then running."

More to come ...