Sydney tightened their grasp on a top-eight spot with a 51-point thumping of fellow finals contender St Kilda at the SCG.
It was a powerful display from the Swans who dominated much of the contest without it being reflected on the scoreboard until they slammed on five unanswered goals in the third term to set up the convincing 12.11 (83) to 4.8 (32) triumph.
While the win lifts the Swans to a 9-5 record the Saints (8-6) slumped to their third consecutive loss since the bye and tumbled out of the top eight for the first time since round three.
With up to 12 teams now fighting for a finals place, the Saints' loss and hit to their percentage turns the spotlight on them ahead of three matches to come against fellow contenders.
Jake Lloyd (39 disposals), Nick Blakey (31, 560m gained), Oliver Florent (27, one goal) and Callum Mills (24) added polish to the Swans performance while Isaac Heeney booted three majors and Tom Papley kicked two.
Fringe midfielder Ryan Clarke performed a crucial role for the Swans in his first minutes of the season after being the unused sub twice, paying close attention to the Saints' in-form half-back Jack Sinclair.
Clarke booted two first-half goals but restricted Sinclair to only a season-low 17 disposals, well below the 28 he had averaged this season, helping to limit the Saints run and carry out of defence.
Dylan Stephens was another unheralded Swan to have an impact, the No.5 pick from the 2019 draft selected for his first match since round three and gathering a career-high 23 disposals.
Saints skipper Jack Steele battled hard in his first match since injuring a shoulder in round nine to collect 27 disposals, while Sebastian Ross (31) and Rowan Marshall (23 touches, 39 hitouts) also contributed but were short on support.
Max King also had an unusually quiet night, failing to kick a goal for the first time since round 11 last year as the Saints ended with their lowest score since 1957.
The Saints have now lost their past seven matches against the Swans at the SCG, a streak that goes back to 2009.
Sydney had only won four opening terms this season until adding another against the Saints with a 3.1 to 1.2 lead at the first change.
They might have stretched that advantage to more than 16 points at the main break but a wasteful 1.5 to 1.0 for the quarter helped keep the Saints in the contest.
But the Swans were able to make the most of their dominance in the second half to run away with the match in front of 31,513 fans in what was the seventh edition of the annual Pride Game between the teams.
St Kilda will need to bounce back quickly in what could be a season-defining month against other finals contenders with a match against Carlton on Friday night while Sydney face Essendon at the MCG the following day.
