LEO BARRY says the Sydney Swans go in as underdogs for Friday night's semi final with the Western Bulldogs.

Barry says the Dogs' form over the season counts for much ahead of the sides' do-or-die clash at the MCG.

"I think the first 15 games answered why they were able to win so many games and show why they are a really good team," Barry said on Wednesday.

The Dogs held a top two spot for most of the season until a late season slump saw them slip to third.

The 2005 premiership defender says the fact the Swans have been largely written off will also work in their favour.

"There's no pressure on us on Friday night. No-one expects us to win."

The Bulldogs and Swans go in to the game with varying form. The Dogs have won one of five games since beating the Swans in round 18, while the Bloods have won three in that time, including two on the trot going into Friday night's final.

Last week, a nervous Bulldogs side was easily beaten by the Hawks while the Swans blew North Melbourne away in Sydney.

"We showed you can turn it (a form slump) around pretty quickly. It was an issue a few weeks ago with a few guys out of form and low on confidence but we've been able to turn it around."

The Swans were 2-6 going into round 22, but have won their last two games convincingly and go into Friday night with momentum.

And the side has done it by reverting back to what it does best.

"On the weekend we made a concerted effort to attack the man and put a lot of pressure on the opposition," he said.

The Swans won the tackle count 75-65 and in a blistering third quarter they smashed North in the stoppages and clearances with Darren Jolly and Brett Kirk doing an outstanding job.

Barry sees this as a key especially with the mobile midfield of the Western Bulldogs.

"They move the ball well through the midfield with guys like Brad Johnson, (Adam) Cooney and (Ryan) Griffen, so our pressure through the midfield will be a key.

"They can tend to get the ball to their forwards quickly, but we believe we have a pretty good forward line, so if we can get the ball to them quickly, we think we can outscore them. Our forward line might stretch them a bit."