Victorious Sydney Swans coach Paul Roos says his side's 35-point triumph over North Melbourne in their elimination final in Sydney on Saturday proves his ageing list is still capable of making waves in September.

The critics - and even Roos himself at times - have publicly questioned the ability of Sydney's seasoned warriors to pose a serious threat in this their sixth consecutive finals appearance.

But it seems Roos' faith has been renewed after the Swans demolished the plucky Kangaroos with a second-half goal blitz to book a semi-final showdown with the Western Bulldogs on Friday night.

"I think at least we showed we're a better team than probably what we were given credit for this year, everyone sort of said (we were) too old and too slow and things like that," Roos said after the match.

But the premiership-winning coach is under no illusions ahead of the Swans' next assignment.

"A week's a long time in footy, we've got a tough game next week against the Bulldogs and generally the teams that lose in the first week of the finals come out and play very well the following week so we know it's going to be an enormous challenge," Roos said.

"The Bulldogs have beaten us twice this year already and they've got some very, very good players."

"But I think at least tonight, winning a final with (Patrick) Veszpremi and (Jarred) Moore and (Kieren) Jack and Marty Mattner coming from another club (Adelaide Crows) and obviously some young guys, it was really pleasing."

He added: "We've got good players playing well, hopefully we've pulled up okay, I'm not too sure how the guys have pulled up, a couple cramped late in the game."

"But we've got some players in good form and we're playing well as a team so at least we (now) give ourselves an opportunity."

Of his side's emphatic second half comeback, which saw his charges land 13 goals to the Kangaroos' five after the break, Roos said: "I felt at half-time we were a really good chance to win the game because we were only 10 points down and I thought we had a lot of improvement left at half-time but we needed everyone to dig in."

He said the performance of key forward Barry Hall was also particularly pleasing.

"He's just such an important player, you can see when he's up and going you can see what a different he makes," Roos said.

"And when we started to get the ball forward and the forwards are marking it and also (getting the) ground balls like they do with 'Goodesy' (Adam Goodes) and Ryan O'Keefe and 'Hally', it's a pretty potent forward line."