The Swans led at every change, to snap the Cats' 29-match winning streak at their home ground, the longest by any club at any venue, with their most recent previous defeat in 2007, to Port Adelaide.
The 15.9 (99) to 12.14 (86) win guaranteed the Swans' finals berth and kept them well in the hunt for a home final, after they started the round in seventh place, but only a small percentage gap behind sixth-placed St Kilda.