Collingwood looms as the big test for Sydney on Saturday night according to coach John Longmire, who says his men are yet to put the AFL on notice.

With four rounds remaining before the finals, the Swans are a game clear atop the ladder.

Victory over the Magpies at ANZ Stadium would be their 10th straight and the 16th for the season – the highest number they’ve tallied in 115 years of VFL/AFL.

They’re in form.

And yet, with a testing run to September that includes games against premiership contenders Collingwood, Hawthorn and Geelong – Longmire is even more wary than usual.

“The reality is the good teams win a lot, that’s why they’re good teams,” Longmire said on Friday.

“You’ve got keep your form for a long period of time. That’s what good teams do and I think we’re yet to prove that.

“Our form’s been reasonably consistent, but we’re yet to prove we can really sustain it.

“We get a big challenge tomorrow against one of the best teams in the competition.”

Collingwood will be minus hard-running midfielder Dane Swan but Longmire expects the likes of young gun Dayne Beams to lift in the reigning Brownlow Medallist’s absence.

“The sense of relief (after Swan was suspended by the Magpies for drinking) just isn’t there, because you know it’s going to be a battle,” he said.

“They’re a super team and play finals footy every week.

“So we expect that type of game, it’s going to be a real hard-fought pressure game in front of a big crowd and our players look forward to that.”

Collingwood’s last-start match was a patchy win over St Kilda, but they do boast a 10-game, six-year winning run against the Swans.

Longmire didn’t want to speculate on what impact another loss could have if the two teams meet again in the finals.

Collingwood star Dale Thomas thought their recent dominance over the Swans would matter for little on the weekend.

“The results of the past are in the past. It’s a different season, the Swans have been going different over the past few years than what they are now and are obviously top of the table,” Thomas said.

Young Sydney on-ballers Luke Parker and Craig Bird will be served with the onerous task of filling the void left by injured veteran Jude Bolton, while co-captain Adam Goodes is expected to spend more time in the midfield.

Longmire said he wasn’t expecting a drop off from his charges, and didn’t believe there was any form of upside to dropping a game before September starts.

“We try to win every game we’re in, whether that’s pre-season, home and away, or finals.”