LATE-SEASON form slumps by contenders aren't uncommon.

After three losses in four games, by a cumulative margin of five points, Sydney was well beaten by the Western Bulldogs on Sunday and suddenly, the Swans' premiership credentials look to be on shaky ground.

Contenders have gone through dips late in campaigns before, but with just a month remaining in the home and away season, the Swans need a response.

Sydney – and Carlton, which has lost three of its past four – only need to look to last year to show how a blip like this can be overcome.

Collingwood lost three of four games between rounds 20 and 23 before reeling off four consecutive wins on the way to the flag.

In fact, Melbourne (2021), Richmond (2019) and West Coast (2018) all endured tough runs during the home-and-away season before winning the premiership.

The Demons won two of six games between rounds 13 and 19, while the Tigers (rounds 11-13) and Eagles (13-15) both lost three in a row.

The Swans have their own history to look back on, too.

In 2012, Sydney lost three of its last four home and away games before rebounding in the finals, culminating in the premiership.

While there is hope looking at recent history, other teams were unable to rebound from late slumps.

In 2015, Fremantle was 16-2 before it lost three of its final four home-and-away games and was eventually knocked out in a preliminary final.

The Bulldogs were flying in 2008 with a 13-1-1 record. But they lost five of their final seven regular-season matches, a qualifying final and then a prelim.

Also exiting in prelims were North Melbourne (2007, lost three in a row between rounds 18-20) and Adelaide (2006, lost four of five between rounds 17-21).

Sitting a game and a half plus percentage clear on top of the ladder, the Swans have a margin of error before September.

But they will be desperate to get back on track soon.