Morton are only one victory away from promotion from Scottish Division Two after demolishing Forfar, whose relegation is now confirmed.
Peter Weatherson scored four, a 20-yard drive and three more clinical finishes, while Jim McAlister fired in one and added another from the penalty spot.
Chris Miller and Bobby Linn headers added to the rout.
Forfar sub Gary Fraser hit back from close range before Chris Templeton slid in a ninth at the near post.
Morton: Mathers, Weatherson, Greacen, Harding, Macgregor, Finlayson, McLaughlin (Millar 64), Stevenson, McAlister (Russell 75), Templeman, McGowan (Linn 64).
Subs Not Used: Walker, McGurn.
Goals: Weatherson 8, 14, Stevenson 21, Weatherson 52, 65, Stevenson 75 pen, Millar 83, Linn 85, Templeman 90.
Forfar: Wood, Lunan, Allison (Lynn 71), Tierney, King, Donald (Tulloch 68), McNally, Tade, Coyle, Stewart (Fraser 77), Lombardi.
Subs Not Used: Beith, Martin.
Booked: McNally, Coyle, Tulloch.
Goal: Fraser 85.
Ref: D Tomney