STEVE Johnson turned back the clock with a six-goal performance in Greater Western Sydney's semi-final demolition of West Coast, but there's no guarantee he'll be there for next week's preliminary final against Richmond.

Johnson booted all his majors against the Eagles in the second half of the Giants' 67-point win, with four coming in the third quarter alone, but the veteran's lingering knee problem means he'll have plenty of work to do to face the Tigers.

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The 34-year-old has battled to get up for back-to-back games this season, and coach Leon Cameron said after the match that it's something Johnson will have to deal with ahead of Saturday's clash.

"It's been a weekly struggle, sometimes he gets up and sometimes he doesn't," he said.

"We'll get a better indication on Wednesday I reckon.

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"Sometimes we've got it right and sometimes we've got it wrong when he's played and his knee is really sore, and clearly he struggles with that.

"We've got to make sure we make the right decision because the stakes are huge (next week), and that makes it even more important.

"In saying that he's a proud and competitive person, he knows that once the year is done that’s it he's finished, so I'm pretty sure he'll be doing everything in his powers to play next Saturday."

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Johnson was recalled for the Eagles game after being dropped for the Giants qualifying final loss to Adelaide, and he managed just three possessions in the first half.

The three-time premiership Cat copped a deep gash to the back of his head in the second term when he was crunched by a pack, and the wound required 15 stitches post-match.

But he returned after the main break, bandaged up and inspired, and earned plenty of praise from Cameron.

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"In the first half it looked like he was trying too hard and sometimes you can do that in finals, and he probably didn't cash in on his opportunities," he said.

"But he kept turning up and clearly he's a special player, so to do that as a 34-year-old is quite unique.

"It's a pretty good performance from a guy who is playing his last couple of games."

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The GWS coach, along with his general manager of football Wayne Campbell, played in Richmond's last preliminary final when they were belted to the tune of 68 points by the Brisbane Lions at the Gabba, so he knows plenty about what his team will come up against at the MCG next week.

There's little doubt the success-starved Tiger fans will be out in force to welcome the Giants to Melbourne, but he said what happens on the other side of the fence won't have any effect on who progresses through to this year's decider.

"It's exciting for our footy club and I was at the Richmond footy club for four years so I know how big the army can become," he said.

"It's great for footy but as soon as that ball bounces, it doesn't matter if there's 85,000 Richmond supports and 10,000 Giants supporters, the result will be determined by the best 22 on the day.

"We feel as though we've regained a bit of mojo in tonight's game, but we need to back it up next week.

"We finished top four for a reason, and the four best sides remaining are probably the best in the competition, but only two will go through.

"If we're any chance we have to produce the pressure that we showed tonight."