Despite a late surge, Sydney were held at bay by Port Adelaide who reclaim top spot with a win at Adelaide Oval.
Holding a 32-point half-time buffer, the Power looked set to canter to victory before taking their foot off the pedal to allow the Swans back into the contest.
The visitors got within 18 points at the final break before Charlie Dixon's stunning fourth goal early in the last term swung back the momentum for the Power, who won 11.7 (73) to 7.5 (47).
After Geelong fleetingly held top spot following victory over the Western Bulldogs on Friday night, the Power wrested it back with just three games left in their season.
Ken Hinkley's men registered 11 forward 50 tackles in the opening term before setting up their imposing lead at the main break through a 30-10 clearance dominance.
A number of tactical moves – including Aliir Aliir into the ruck, Callum Sinclair forward and Tom McCartin to defence – had the Swans hold the Power goalless in the third term.
The Swans could have bridged the margin more at the final break had they taken their chances in front of goal.
Battle of Nic Nat's understudies
Scott Lycett (2018) and Callum Sinclair (2015) both departed West Coast to become No.1 ruckmen after spending time behind Nic Naitanui. On Saturday, Lycett took the points as they met again. The Power dominated the first-half clearances 30-10, despite Sinclair leading the Swans to a 21-19 hitout count.
It prompted Swans coach John Longmire to swing Sinclair forward, with Aliir Aliir replacing him in the middle to arrest the differential and Tom McCartin moving back and holding his own on Charlie Dixon. The only dampener on Lycett's day was a brutal falcon during the third term.
Butters melts under no pressure
Power second-year sensation Zak Butters looked set to waltz into an open goal and extend his side's lead during the first team. But after two quick bounces, Butters stumbled before hyper-extending his left knee in what appeared a nasty incident.
Fortunately, it had no impact on his day, the 19-year-old continuing his hot recent form to finish with 13 disposals and a goal.
Ebert's nasty egg after head clash
After a well-documented series of concussions, Brad Ebert's heavy head knock had the Power officials holding their breath in the third term. The veteran was taken from the ground for assessment before re-emerging with a monster egg on his right cheekbone.
Incredibly, he returned to the field in the final term to play out the match.
A game for the veterans
The milestone man Jake Lloyd was instrumental in his 150th, amassing 31 disposals and 7 marks. The ever reliable Josh Kennedy stepped up to the plate with 28 disposals, and 4 tackles.
PORT ADELAIDE 4.3 8.3 8.4 11.7 (73)
SYDNEY 3.1 3.1 5.4 7.5 (47)
Port Adelaide: Dixon 4, Gray 2, Sutcliffe, Boak, Wines, Butters, Westhoff
Sydney: Reid 2, Papley, Sinclair, Dawson, Blakey, Bell
Port Adelaide: Gray, Wines, Rockliff, Dixon, Boak, Powell-Pepper, Lycett
Sydney: Kennedy, Lloyd, Dawson, Papley, Clarke, McCartin
Port Adelaide: Ebert (cheekbone)