THE Sydney Swans thrashed North Melbourne in last year's first preliminary final on several fronts, but it was their aerial dominance in attack that left the Roos shell-shocked. 

The Swans took a staggering 27 marks inside their forward 50 in their 71-point win at ANZ Stadium, while the Roos could manage just nine inside their attacking arc. 

The Swans' tally was the highest in last year's finals series, with Port Adelaide (23 in its 57-point elimination final demolition of Richmond) and Geelong (19 in its semi-final loss to North) the only other teams to take more than 17 inside 50 marks. 

Not surprisingly, it was Lance Franklin, 197cm, and Kurt Tippett, 202cm, who did most of the damage against North. 

Franklin took eight marks inside the Swans' forward 50 that night, while Tippett was not far behind him with six. 

The twin towers cashed in on the scoreboard too, with Franklin kicking five goals and Tippett four. 

Scott Thompson, who spent much of last year's final on Franklin, told AFL.com.au that North was determined to avoid a repeat of the Swans' forward-line blitzkrieg in Saturday night's first semi-final at ANZ Stadium. 

"We'll be hoping to bounce back and not put in a performance like that again," Thompson said.

"They were two great players on the night and they've been great players.

"But, hopefully, we can structure up a bit differently and we can combat their marking ability."

The Roos' task will be made easier by the absence of Franklin, who won't play again this season because of a mental health condition, and fellow tall Sam Reid, who suffered a season-ending hamstring injury in last Saturday's qualifying final loss to Fremantle.

But Thompson is not about to underestimate the Swans, knowing that with Tippett and two-time Brownlow medallist Adam Goodes, Sydney still has formidable pillars to build an attack around. 

"It will be interesting to see what they do, but they're a great team. They play finals footy the whole way through the year, so whoever they bring in we're expecting them to be at their best," Thompson says.

"They're such a good team, whoever they bring in they just play their role, so it's not going to be too much different."

The 2013 All Australian full-back is confident, however, that the Roos can handle whatever forward-line structure the Swans throw at them, saying their backline is in far better shape than it was this time last year. 

For one, Lachlan Hansen will take his place in defence on Saturday night. 

The 197cm defender missed all three of North's finals last year with injury, and his ability to short-circuit opposition attacks with his intercept marking was sorely missed when Franklin and Tippett were running amok.

Thompson also believes that North is better placed generally this year after it rested nine senior players, including himself and fellow defenders Michael Firrito and Sam Wright, from the round 23 team that took on Richmond.

The defender says the Roos hit a brick wall in last year's preliminary final after draining finals wins over Essendon and Geelong, but will enter Saturday night's game feeling far fresher.

"We're in a bit of a different situation. Last time they were coming off a week off and we'd just had two great wins," Thompson says. 

"This year (some of us had) a week off round 23 and we ran out the game really well against Richmond. We were pretty happy with that. 

"I think everyone's a bit fresher this year and we'll be looking to obviously win this game and we want to go pretty deep into the finals."