OUT-of-form Sydney players will face the chopping block for Sunday's AFL crunch game against Fremantle at the SCG, Swans coach Paul Roos says.

The back-to-back grand finalists have lost three of their last four matches and are currently one win and percentage out of the eight, putting their finals chances on shaky ground.

They suffered an honourable 18-point loss against ladder leaders Geelong at Skilled Stadium on Saturday, coming within 11 points during the last quarter despite trailing by 41 at the main break.

Roos said he was as happy with the team as he had ever been coming off a loss, but said selection changes were in store.

"They did play a lot better and some guys got into some good form, [but] there's probably still a couple of guys that we still need to talk about in terms of form and maybe get some guys in the seconds," he said.

"We just need to keep making sure we give the guys a chance to either get into form in the seniors or go back and play seconds and get back into form.

"So there's probably some selection decisions [this week]."

Roos was pleased with the Swans' efforts, but said they would have to maintain their self-belief to match Fremantle, who crushed Carlton by 77 points on Saturday.

"The competition is very even, every team is capable of beating every other team and at any given moment, we've already seen that this year," he said.

"We know if we don't come and play well Freo will beat us, regardless of whether they won or lost last week."

Roos said it was too early to decide whether Barry Hall will play, who spent the Geelong game in the coaches' box after ruling himself out last weekend with a groin injury.

"I am expecting him to play based on the discussion we had last week, but I haven't had any update as to how his feeling, so we will have to wait and see," Roos said.