GREATER Western Sydney coach Leon Cameron has admitted that his choice to play veteran Steve Johnson in last week's win over Richmond backfired.

Johnson, who has been struggling with a knee problem all season and missed the Giants' round four win over Port Adelaide, pulled up sore again after his last-minute heroics against Collingwood in round eight, but played against the Tigers last week.

The 33-year-old was ruled out of the club's clash with West Coast on Sunday earlier in the week, and Cameron acknowledged that the decision to play a sore Johnson was a mistake, and probably wouldn't have occurred if the GWS injury list wasn't so stacked with stars.

"We rolled the dice with him last week even though he probably shouldn't have played, the knee is getting pretty bad at the moment," he said.

"There's no doubt we probably pushed it too far with him, and if we had have had a couple of guys that were ready to play AFL footy, we would have gone down a different path.

"In saying that, I also backed Steve in as we have done a number of times, and I think a number of clubs do that with one or two players every week.

"A lot of these guys that have been in the system for 10 or 15 years can play with these sorts of injuries, but his knee just seems to be blowing up a bit throughout and at the end of the game.

"It's restricting him a little bit, but hopefully we can get it right over the next seven to 14 days."

Johnson will be absent for Sunday's game against the Eagles, and may possibly miss the Giants' match to Spotless Stadium against Essendon next week, but could return against Carlton at Etihad Stadium in round 12.

Cameron said the club might look to rest the 2007 Norm Smith medallist for the Blues game given they have the round 13 bye, to give him extra time to get the knee right, but that situation seems unlikely.

"I think if you have a full list of players you get that opportunity, but I don't think we're in that position at the moment," he said.

"If he's right to go in one or two weeks we'll play him, going on results and where we're at, and what our form is like in the ones."

Academy draftees Matthew Kennedy and Harry Himmelberg appear certain to replace Johnson and big man Rory Lobb (groin) for the Giants' trip to Perth.