GEELONG captain Tom Harley could play against Melbourne on Sunday, although another week on the sidelines seems more likely.

Harley, 30, had knee surgery after last year’s grand final and was expected to be fit for the NAB Cup pre-season competition, but the injury has lingered.

The Cats' backline has also missed Josh Hunt, sidelined with a season-ending knee injury, so word that Harley's return is imminent is a boost for the undefeated side.

Geelong coach Mark Thompson was clearly happy with the prospect and said Harley would likely play in round seven if he didn't prove his fitness this week.

"He's 50-50," Thompson said from Skilled Stadium on Tuesday afternoon.

"It'll get down to how he trains and how he's feeling and whether the medicos give him the all-clear to play this week, and if he's ready to play.

"I'd like to think that he could play in the AFL. I haven't taken that to match committee yet but I think most of the match committee would agree with that.

"He's our captain. He deserves to play up."

Thompson said it had been difficult for Harley to sit in the stands watching his side start the season without him.

"It's been really hard for him mentally, because he just wants to play, like most players," he said.

"He hasn't been able to do much over summer, so he must be pretty excited that he's so close."

Thompson said Harley stabilised Geelong's defence and his recall would go some way towards settling the group for the rest of the year.

He added that the skipper brought a list of important attributes.

"He's just a good person in the team," Thompson said.

"He intercepts the ball from the opposition kicks, his strength and leadership, the way he communicates with his teammates is just outstanding. It's first-class.

"When we get challenged, or times are tough, or when you need to be motivated, he's always out saying the right things.

"He's just a little replica of our match committee."