The Sydney Swans have started their pre-season in impressive fashion with a come from behind victory over GWS Giants on Friday night.

Thousands turned out to watch the Swans win by 26 points over their cross town rivals at Henson Park in Marrackville.

Players shook hands after the third quarter believing the contest was over, but despite having no floodlights to play under, the clubs agreed to a further 10 minutes of action.

The Swans won 11.11 (77) to 7.9 (51) with contributions from young and old players alike. 

Lance Franklin played just the first half, kicking one goal, before putting his feet up, while George Hewett, Jake Lloyd and Dane Rampe all impressed.

Draftees Ryley Stoddart and Tom McCartin were among the goalkickers.

For GWS, Jon Patton looked menacing in the forward 50, while Lachie Whitfield found plenty of the ball through midfield.

With a strong breeze providing a distinct scoring end, the Swans led by 21 points at quarter-time before the Giants piled on five unanswered goals in the second to take a half-time lead.

Sydney again dominated the third quarter, kicking six goals to one, to finish easy victors. 

The Swans travel to Brisbane next Saturday to take on the Lions in the JLT Community Series, while the Giants open their campaign on Thursday night in Canberra against Collingwood.