Defender Lachie Henderson has undergone knee surgery, delivering a pre-finals blow to AFL premiership contenders Geelong.
The Cats are unsure how long Henderson will take to recover from Tuesday's arthroscopy but are upbeat he will play again this year.
"The timing of Lachie's injury isn't ideal but the pre-finals bye will gift him with more time to recover," Geelong football manager Steve Hocking said.
"Lachie has been an important part of our team this year and we are optimistic he will see finals football."
Former Carlton and Brisbane utility Henderson has impressed in his first season at the club, playing 18 games predominantly in defence.
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Henderson has helped Geelong fill the void left by Jared Rivers' retirement last year.
The 26-year-old also loomed as a key forward up the sleeve of coach Chris Scott, who spoke earlier this month about the prospect of throwing Henderson and Harry Taylor into attack during September.
"We're very confident that Lachie can play forward for us," Scott said after adopting the tactic in a win over Richmond.
"It's an option that we've talked about a lot. I'm sure we'll continue to talk about it."
Henderson started forward and kicked two goals against former side Brisbane before hurting his right knee during the fourth quarter of the Cats' 60-point win at the Gabba.
