JOSH Kelly is a chance to play next week should Greater Western Sydney beat Collingwood in Saturday night's semi-final, but the star midfielder could require surgery on his injured knee at the end of the season.

Kelly injured the meniscus in his right knee in the opening term of last week's 49-point win over Sydney at the SCG and missed the rest of the game, and while the Giants remained optimistic throughout the week, he couldn't be considered for the club's clash against the Magpies.

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The positive news for Kelly is that specialists have given the silky midfielder the all-clear to continue his rehabilitation in an attempt to recover in time should the Giants get past the Pies.

Speaking at Sydney airport before his team boarded their flight to Melbourne on Friday morning, GWS coach Leon Cameron the decision to leave the club champion out of his side was an easy one.

"We understand the importance of finals footy, but we would never risk a play of Josh's caliber, just to play one game and put him in danger," he said.

"It's not like there's no hope (he can get back this year), there's a lot of hope."

Kelly has been replaced by veteran Ryan Griffen, who returns for his first game since he suffered a hamstring injury against Sydney in round 22.

The 32-year-old had a frustrating end to the home and away season with two separate hamstring issues, but his experience in playing 13 finals for the Giants and the Western Bulldogs will be crucial against Collingwood.

Griffen has played predominantly as a defensive forward in 2018, but Cameron said he can help replace Kelly in the team's midfield rotation, along with the likes of Brett Deledio and Tim Taranto, who both spent time inside 50 last week.

"He's a big-game player, he plays really well in finals, and he's not going to be overawed by the occasion," he said.

"It's great having him back because he wins contested ball which is what finals footy is all about.

"He knows what he's got to do on Saturday night and it will be a challenge for him, but we have the upmost faith in him."

Former Magpie Lachie Keeffe has also come into the Giants' team at the expense of the unlucky Harry Perryman to provide some more height in defence, which will allow co-captain Phil Davis more freedom to be an offensive presence in the back half.

He's likely to get the job on Collingwood's tallest deep target in Mason Cox, with Davis released to mind the mobile Brody Mihocek further up the ground.

"Cox is 211cm and Mihocek is about 195, Will Hoskin-Elliott and Jaydyn Stephenson can play tall, so we've got to be mindful (of that)," he said.

"We also want to have some flexibility with Phil as well.

"They've got a very good forward line and it's probably one of their greatest strengths."