Morton won to overtake opponents Raith Rovers and move up to third in the table.
Raith's Stuart Anderson tested goalkeeper Derek Gaston and Scott Taggart's long-range drive sailed wide of the visiting goal in the first half.
Stephen Stirling's thunderous 25-yard strike broke the deadlock midway through the second half.
Simon Mensing headed over and Jason Thomson fired wide as Raith chased an equaliser.
Morton: Gaston, Taggart, Reid, Mark McLaughlin, Dyer, Stirling, Bachirou, Tidser, Graham, Weatherson, Campbell (Gormley 79). Subs Not Used: Hutton, Wallace, O'Ware, McDaid.
Booked: Taggart, Dyer, Stirling.
Goals: Stirling 67.
Raith: McGurn, Thomson, Mensing, Hill, Malowne, Smith, Stuart Anderson, Walker, Hamill (Grant Anderson 78), Brian Graham, Greig Spence. Subs Not Used: Laidlaw, Ellis, Donaldson, Callachan.
Booked: Brian Graham, Mensing, Hill.
Ref: George Salmond