Jack Lukosius will need surgery on a fractured kneecap in a major injury blow for Port Adelaide.
The former Gold Coast forward suffered the injury early in Saturday's comfortable win over Richmond.
Port will also be without Ryan Burton (hip) and Lachie Jones (adductor) for Thursday's home game against winless Essendon.
Lukosius suffered the injury in a collision and the Power said on Sunday he would be sidelined "for an extended period".
He was hurt only a few minutes into his first home game for the Power. Lukosius tried to return to the field, but clearly was not right and was substituted out of the game.
It is a major setback for Port, who recruited Lukosius in last year's trade period.
"Lukosius will undergo surgery in the coming days, with a timeline for return to become clearer soon," the Power said in a statement.
Port are also without star on-baller Zak Butters (knee), forward Todd Marshall (Achilles) and defender Brandon Zerk-Thatcher (back).
