GREATER Western Sydney is likely to be without star forwards Toby Greene and Steve Johnson, plus defender Zac Williams for this week's clash with Hawthorn in Launceston.

Greene, a late withdrawal from the Giants' draw with Geelong last week with an ankle problem, and Johnson (knee), both failed to take part in the main training session at Spotless Stadium on Wednesday.

Johnson has a recurring knee issue that caused him to be managed earlier this season, and could see him miss more games between now and the finals.

Williams (hamstring) was also a late withdrawal from the Cats clash and failed to join the main group on the track, instead being restricted to rehab running.

GWS will train again on Friday but unless the trio made some significant improvements, coach Leon Cameron said it was unlikely they'll make the trip.

"Toby's ankle has taken a bit longer than we thought it would which is disappointing," he said.

"It can turn around pretty quickly and if he trains on Friday then we'll play him, but you'd have to say he's a lesser chance to play this weekend.

"Steve is really sore, he's a big chance to miss as well with his knee and probably some general soreness.

"The game on the weekend took a fair bit out of him but in saying that he did present a bit better today.

"We're also mindful of how many games he can play in a row and the game was really brutal on the weekend, so he's 50/50 as well.

"Zac is probably in a better position in the other two but when you're dealing with a minor hamstring you have ask could he get back in nine or 10 days?

"It would be disappointing if all three couldn't get up but that’s the way it is."

With last week's first-gamer Jeremy Finlayson (knee) already ruled out, Cameron could need to make at least two changes for round 16, with GWS academy draftees Harry Perryman and Will Setterfield in the selection frame.

Setterfield, who had 31 possessions, 18 tackles and kicked two goals in the NEAFL last week in his second game back after suffering a serious ankle injury in round three, would make his debut if picked.

The fifth overall selection at last year's NAB AFL draft is a talented midfielder with outstanding skills by hand and foot, but Cameron said he might need more time in the reserves after such a long layoff.

"We were rapt with his game, it's a pretty good return for a kid playing his second game in 12 weeks," he said.

"In saying that, the step up from the NEAFL to the AFL is huge.

"In a perfect world we'd probably plan to play him in three or four weeks, but as we know this game isn't a perfect world, and it might come earlier than we first thought.

"Each week he's progressing to take his opportunity to play and we're really rapt with that."

Sam Reid (ankle) should be right to play against Hawthorn after managed to get through Wednesday's session.

The utility was on light duties but looked to be moving without any major discomfort.