IT'S lucky for Craig Bolton that he enjoys a challenge. It's even more fortunate for the Sydney defender that the anxiety he used to suffer over his football is a thing of the past - otherwise, he'd be a wreck.

Defensive partner Leo Barry has missed the past three matches through injury, and Bolton has become the cornerstone of the Swans' back line. In that time, he has played on three matchwinners - Richmond's Matthew Richardson, Melbourne's David Neitz, and St Kilda's Fraser Gehrig.

And after he limited the three to a point, a goal and two goals respectively, to say Bolton has been impressive would be an understatement .

"I like playing on the good players. It's always a challenge," said Bolton, again one Sydney's best in their win over the Saints. "If you set yourself for those big names, as it has been in the last few weeks, you really get up for the game. If you're a key defender and you're playing against St Kilda, you know you're going to get either Gehrig or [Nick] Riewoldt - so there's not too much of an up-side.

You've got to look at it as a challenge. I'd never played on Gehrig before and Teddy [Richards] had never played on Riewoldt, so we knew it was going to be a big game for both of us. I think the midfield really shut them down in the second half and starved them and made our job a lot easier.

"It's been a bit different down there [in defence] this year. Leo's been out, Tadhg's [Kennelly] been out, Mal's [Nick Malceski] come into the defence and Lewie's [Lewis Roberts-Thomson] been out for the year as well.

"There's been a bit of adjustment and getting used to the guys, because it really is important to know the guys you're playing with every week down there. Hopefully we're starting to get some consistency - and once we get Leo back, we can have a pretty solid back six going into the finals."

Since moving to Sydney from Brisbane at the start of 2003, Bolton has figured in all but one of the 118 games the club has played and is regularly among the best on the ground.

And any signs of the pre-match nerves that used to plague him are long gone, much to the credit of coach Paul Roos. "I used to be [anxious] a lot more, but I'm a lot more relaxed now," Bolton said. "It's only footy, Roosy always says, and it's true.

"No doubt it's Roosy and since I've come down here," Bolton said when asked how the turnaround had come about. "In Brisbane, I was a very nervous, waiting for that next mistake … but Roosy cracks a joke every now and again before a game and has done since I got here and made me feel comfortable with how everything is going."

Things don't get any easier for Bolton and his fellow defenders. In the next three weeks, he's set to line up against Jonathan Brown, Anthony Rocca and then Hawthorn's emerging superstar, Lance Franklin.

Roos admitted Barry, who was a late withdrawal on Saturday because his hamstring injury flared up after Thursday's training session, was no certainty to play in Brisbane on Saturday. "He'll be touch and go - I'd say he'll be 50-50," Roos said. "We don't want him to redo it and miss three or four weeks. We'll have to take it a little more carefully now."