Sydney coach John Longmire has fired a warning shot by declaring the red-hot Swans still have room for improvement after chasing down Geelong on Sunday to clinch an eighth-straight win.

The Swans trailed by as much as 35 points as the Cats booted the opening six goals, but then slammed on the next five majors in nine minutes to set up a 30-point victory at the SCG.

Longmire conceded he is concerned with his side's slow starts this year, after they also allowed Carlton to race away to an early lead with the opening four goals in their previous match at their home ground.

Overall, the Swans have trailed at quarter time in half of their 12 matches so far this year, despite losing just one game for the season.

"We've still got a bit of work to do on our starts," Longmire said.

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"Probably for the last month, we've been aware of it a little bit and today we certainly got exposed.

"We got beaten in contested ball or around the footy, a fair bit in the air in that first quarter, and in the second quarter we turned that right around. (We were) really strong in all those areas as the game went on.

"That was really good to be able to turn that around but we can still get off to a better start."

The Swans got on top as Brodie Grundy asserted himself with 21 contested possessions among his 25 disposals, while Isaac Heeney, Chad Warner and Errol Gulden again ran rampant in the midfield.

ROUND 13 HIGHLIGHTS

Tom Papley booted four second-half goals including a long bomb from the edge of the centre square, while emerging key forward Joel Amartey was a threat throughout and added three majors.

Goalsneak Papley had an opportunity to repeat his long-range effort from a similar spot just minutes later but instead passed to Justin McInerney, who tugged his kick wide.

Papley had multiple goals in just three games this year before Sunday, well below his normally prolific goalscoring standard, but his selflessness has not gone unnoticed.

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"If you look at some of the team-orientated focused acts he's done in the first half of the year, it has been really strong," Longmire said.

"At the time I thought he could have just taken a deep breath, taken another 30 (seconds), had a shot. But it's hard to knock someone who's having a go at trying to bring a teammate into the game."