St Mirren, Peterhead and Queen's Park have all advanced to the semi finals of the Scottish Challenge Cup with quarter-final wins over Dunfermline Athletic, Stenhousemuir and Elgin City respectively.
Mallan recorded a brace by firing past Pars keeper Sean Murdoch two minutes from time, giving the Saints a 4-0 victory.
Peterhead, similarly to St Mirren, struck three times in the first half against fellow League One side Stenhousemuir to record a comfortable victory.
Elgin pulled one goal back early in the second period as Darryl McHardy breached the Queen's Park defence, but they were unable to find a leveller as they dropped out of the Cup at the quarter-final stage.
Rangers play current holders Livingston in the competition's last quarter final on October 20.