Coach Paul Roos felt Sydney produced the worst football he had seen in his six years at the helm in their listless 40-point thrashing by the Western Bulldogs at Canberra's Manuka Oval on Saturday.

The Swans came into the game nestled in the top eight and coming off their first two-game winning streak of the season, but it all went horribly wrong in a dreadful 18.9 (117) to 12.5 (77) thrashing that leaves them stuck in the middle of a congested ladder.

Sydney actually started well, kicking the opening two goals through Barry Hall, but the Dogs then kicked the next 13 goals unanswered to demoralise the Swans and leave Roos scratching his head.

"First 10 minutes (we were okay) and then after that we struggled, it was about 40 minutes where they kicked 13 goals to nothing at one stage," he said.

"It was probably 40 minutes of our worst footy we've played in six years.

"They've got to take some credit, because they played really, really well."

Roos labelled the effort "deplorable" and admitted he felt "helpless" as he tried to find a solution to his side's woes.

The only positive for the designated away team was they were able to limit the damage by kicking 10 goals to five after halftime and reduce a margin that at one stage stood at a commanding 70 points.

Hall finished with six goals, while fellow veterans Ryan O'Keefe, Brett Kirk and Adam Goodes held their own, but it was a sorry story for most in red and white.

The Bulldogs showed they weren't carrying any disappointment from last week's two-point loss to Geelong, with Scott Welsh kicking four goals and Daniel Giansiracusa, Mitch Hahn and Callan Ward kicking three each.

Both sides came into the game with 5-4 records and it is the Bulldogs who have kept on track for the top four with an impressive display.

"Great win. If you said before the game we were going to win by seven goals, you would certainly be surprised by that," Dogs coach Rodney Eade said afterwards.

"But our effort all day was terrific against a team that is obviously fighting with us."

Sydney were coming off their best win of the year when they hammered Port Adelaide at the SCG on the back of a blistering first quarter, a result that had pundits talking up their chances of a seventh straight finals appearance.

But Roos joked he was looking for an early flight back to Sydney at the end of a dismal first half on Saturday.

"It's frustrating, we probably followed our best performance with our worst," Roos said.

"Our guys probably had their worst games of the year and they all had them on the same day.

"You can't expect to do very well if individually you're down on form. It makes it hard against average opposition, let alone very, very good opposition."

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