Sydney coach John Longmire warns his side must improve on a last-start victory over Collingwood if they hope to be competitive against Hawthorn in Saturday's AFL grand final.

The Swans impressed plenty in their preliminary final against the Magpies, winning by 26 points despite kicking an inaccurate 13.18.

It was in stark contrast to the Hawks' five-point triumph over Adelaide last Saturday, in which the overwhelming favourites were made to sweat.

But Longmire said on Monday the onus was on the Swans to do all the improving, otherwise the premiership decider would be a one-sided affair.

"We'll have our review today, we'll look at things we did well," Longmire said.

"But also the things we can get better at, and there were some.

"We have to get better at some things if we're going to be competitive this week, and we'll address that and move onto the Hawks straight away."

The Swans have one victory from their past 15 clashes at the MCG, but Longmire dismissed the hoodoo.

The second-year coach was more worried about recent memories of Hawthorn's come-from-behind win in round 22 at the SCG, in which the Swans held a 38-point lead in the second quarter.

"You've got to do a lot of things right (to beat Hawthorn)," he said.

"You've got to make sure your pressure is absolutely elite, and elite for four quarters.

"You've got to take your chances when you get them."

Along with better goal-kicking, one of Sydney's keys to victory will be getting the most out of centre half-forward Sam Reid.

Reid has been held to a total of one goal and five marks in the Swans' two finals this year.

Some pundits suggest the 20-year-old is down on confidence and form, but Longmire was quick to defend his efforts since missing the final game of the regular season with a glute strain.

"He's dropped a few marks on the weekend ... his pressure was pretty good. He's an important player to our team," Longmire said.

"If you have a look at the game (against Collingwood) again, he got a couple of great intercepts.

"His wingspan is enormous ... when he can use his speed, get across the ground so quickly, it puts pressure on the opposition and doubt in the opposition when they've got the footy."