Sydney are optimistic Sam Reid has only jarred his knee and will be available for the grand final after his injury scare on Friday night.

The young forward was subbed off at three-quarter time after limping off the ground shortly before the final break.

The Swans are unsure what damage, if any, Reid has sustained to his right knee though he was not wearing any ice immediately after the game.

"He jarred his knee. I think he's okay but we'll have to see how he goes during the week," said Swans coach John Longmire.

"We took a conservative route at three-quarter time and didn't want to push him along. He says he's okay."

Although not having the star quality of his fellow towers in the forward line, Reid plays a key role in the Swans team as a marking forward and occasional relief ruckman to Mike Pyke.

Reid's injury scare was the only matter of concern for the Swans, who recorded an emphatic 71-point preliminary final thrashing of North Melbourne in Adam Goodes' 350th game.

Goodes played a key role with three goals in one of his best matches of the year.

"I thought his second half last week was pretty good, I think his first half wasn't as good as he would have hoped for then from the first bounce tonight he was running on top of the ground," Longmire said.

"Certainly that run on the outer side across that wing. He took off and I was thinking he should get rid of it pretty soon.

"He took a couple of bounces and he kept going, he's still got it. We saw it a few weeks ago at Etihad Stadium against the Bulldogs as well when he had that speed, I think it's still there."

The Swans had 25 more inside 50 entries and 21 more scoring shots over the Kangaroos, who were no match for the premiership favourites after the opening 15 minutes of the game.

The win secures the club their fourth grand final appearance in 10 years and has them on track for a second flag in three seasons.

"You've got to take it for what it is and enjoy this moment. They're hard to get into," Longmire said.

"It's hard to win a preliminary final. I was at a club [North Melbourne] where we played in seven preliminary finals in a row. We got to three grand finals and only won two flags.

"It's a difficult thing to do to win a prelim final.

"You've got to enjoy that moment tonight then you get your injuries attended to, your sore spots, get up tomorrow then enjoy the week, know what it's about and switch on and switch off at the right times, which hopefully the majority of our players will do well."

The Swans could not have hoped for a better lead-up to this year's decider after playing two home finals and not having travelled in the past month.

"It's panned out the way we wanted it to but we've still got two-and-a-half hours of pretty solid footy next week," Longmire said.

"Next Saturday doesn't come any bigger or hotter, regardless of the preparation we've had we'll have to be at our best."