AFTER two comprehensive defeats to Hawthorn and Collingwood, Sydney Swans coach Paul Roos says the side must get back to basics.

The Swans remain fourth on the ladder but failed against fellow top-four aspirants and will need to lift considerably to be a premiership threat.

Concerned about the leaking of easy goals, Roos called for his defenders to get back to basics to stop a slide out of the top-four.

"Our forward line was probably the least of our worries on the weekend, it was actually really one of the few positives.

"Defensively we've obviously let ourselves down the last couple of weeks, and the defenders will admit that and have been pretty disappointed.

"Generally we're pretty hard to score against. Our defenders just need to get back to basics footy and get the ball to ground, spoiling really aggressively.

"The last couple of weeks we've struggled in that area and it's something that we need to address."

Nick Malceski will return from a calf injury for the round 16 clash with Carlton at Telstra Dome on Sunday but Nick Davis, who was likely to make a return from the lower grade, dislocated his knee on Sunday, ending his season.

Swans running half-back Tadhg Kennelly had his shoulder dislocated twice in the Swans 31-point loss to the Hawks but Roos has played down the problem.

"It's was probably more obvious on the weekend because it came out a couple of times, but he's certainly been playing with it most of the year and, in a sense, the fact that is slips out so easily is probably positive because it goes back in so easy," he said.

"As soon as it goes back in there's no pain and he can function with it and all those sorts of things.

"I suspect at some point he might have to have an operation but at the moment, provided he's training well and his confidence is good, he'll keep on playing."