Gray was superb, midfielder Brad Ebert (three goals, 25 disposals) and Sam Gray (37 possessions) were prominent, and the brilliant Chad Wingard and trump recruit Charlie Dixon each kicked three goals.
Their feats helped Port overwhelm a Saints side inspired by Tom Hickey, who ruled the rucks with 56 hitouts and 20 disposals in an eye-catching performance.
Hickey fed a hungry St Kilda midfield led by Jack Steven (36 possessions), David Armitage (28 touches) and 250-gamer Leigh Montagna (29 disposals).
With lively goalsneak Jack Lonie scoring three goals, the Saints stretched out to a 21-point lead some 21 minutes into the third term.
But Port, who lost fleet-footed Matt White to a suspected pectoral muscle tear in the first term, stormed home.
Advertisement
Robbie and Sam Gray, Wingard and Ebert lifted the home side, while former Gold Coast forward Dixon added menace.
Dixon provided a solid target but was wayward in front of goal before icing the result with Port’s two last goals of the match.