With Sydney star Errol Gulden on track to return from injury, Swans coach Dean Cox is well aware of the selection headache looming.

Explosive winger Gulden has circled the club's round-16 fixture against Brisbane to end his three-month lay-off from a dislocated shoulder.

The 23-year-old hasn't played since the Swans played the reigning premiers in round one, after a fractured ankle kept him to 10 games last season.

But unlike last year's sub-par 10th-place finish, Sydney have enjoyed a barnstorming start, with Justin McInerney impressing in Gulden's absence.

Fresh off a 114-point mauling of Richmond, the Swans sit second (10-2) behind leaders Fremantle (11-1).

Gulden's imminent return is slightly ahead of schedule, with the club initially expecting a four-month stint on the sidelines.

"From meeting with the surgeon, even before the work he's put into getting himself in the best condition, we always knew that was going to happen," Cox said on Friday.

"We expect, if there are no hiccups, that he'll play that Brisbane game.

"Compared with his ankle last year, he was really slow trying to get back to doing what he does best - that's cover the ground and kick the ball as often as he possibly can.

"He's been doing that for five or six weeks now."

Cox already had a selection conundrum to mull over ahead of Sunday's SCG clash with St Kilda, after playing Pete Ladhams in the ruck and Hayden McLean in a four-pronged attack against the Tigers.

Ladhams and McLean remain in the extended squad, though in-form ruck Brodie Grundy (managed) will return against St Kilda, alongside livewire forward Malcolm Rosas Jnr (ankle).

St Kilda boast two rucks in Tom De Koning and Rowan Marshall, with fit-again Nasiah Wanganeen-Milera (calf) headlining their changes against Sydney.

"Yeah, tough one. They're always going to be tough decisions ... whether it's four talls again, whether we play two rucks," Cox said.

"They've obviously got Marshall and De Koning as well, so that's something that we've spoken about all week and what it looks like.

"But Brodie's coming back in. He's been one of our best players all year ... it's just what we do and how we surround him."

Swans skipper Callum Mills (calf), Joel Hamling and Matt Roberts (groin) are also in the extended squad, for Tom Hanily (omitted) and Lewis Melican (hamstring).