Sydney Swans coach Paul Roos says a back to basics approach is behind his side's dramatic late-season form reversal.

The Swans backed up their final-round defeat of the Lions with an impressive 35-point win over the Kangaroos in last weekend's elimination final to book a semi-final showdown with the Bulldogs at the MCG on Friday night.

Asked the secret to his side's much-improved play, Roos said a return to the accountable style that has propelled them into the post season six years in a row was significant.

"I think we obviously got a lot of confidence out of the Brisbane game and just the way we're attacking the footy is a lot better over the last couple of weeks and just getting back to I suppose basic football really," Roos said.

"When you look at guys like 'Kirky' (Brett Kirk) and Jude (Bolton) and (Jarrad) McVeigh, the way they went about the football in the midfield and the forwards (played) in front (of their opponents) and the defenders getting back to just some real basic spoiling."

"We've wound the clock back which has been good and it's allowed us to win a couple of games in pretty good fashion."

Roos credited the club's elder statesmen for seizing the initiative and sparking the dramatic turn around.

"It all starts around the footy and the leadership group have really stood up the last couple of weeks and when your better players are playing well it make it a lot easier for everyone," he said.

While things are looking up for the Sydney siders, it's a vastly different story for Rodney Eade's men who have won just one of their previous five matches.

But Roos remains wary of the embattled Bulldogs heading into the do-or-die clash.

"Two weeks ago people said we were finished and dead and buried so it can turn around reasonably quickly," Roos said.

"They've beaten us twice (in 2008) so we'll probably take (notice) of those games rather than their most recent form."

"They've played well against us, they've had two really good quarters where they've kicked eight and seven goals … so probably our main focus is on their absolute best."

"We always prepare for the opposition's best and their best is very, very good so we're going to have to play well again to compete."

Despite the two side's contrasting fortunes in recent weeks, Roos said past results would have little bearing on the outcome of the clash.

"History tells you it's very hard to keep on winning in finals so we expect them to come out really hard like North did at the start of the game," he said.

"I think in finals footy there's pressure on everyone, if you lose you're out so it's the same for us as it is for the Bulldogs."