O'Brien out for Montrose
Morton are without David O'Brien against Montrose after he suffered a thigh injury in the 3-1 defeat against Dumbarton on Saturday and an ankle injury continues to keep Joe McKee sidelined.
Manager Allan Moore is likely to make changes to his defence against the League 2 side after being disappointed with his back-line at the Bet Butler Stadium.
He said: "We lost goals we shouldn't be losing and that has to stop.
"It is good to have this game so quickly after Saturday's disappointment as we have the chance to get going again. We need to defend better and also be more ruthless in attack."
Montrose head to Cappielow without weekend goalscorer Paul Watson, who was dismissed in their win against Arbroath in the last round of the competition.
Goalkeeper Sandy Wood, who has a hip problem, remains out as well with Links Park manager Stuart Garden looking for his men to carry on where they left off on Saturday.
Garden said: "We ended very strongly against Berwick and deserved more than the draw. If we can reach that level of performance early and stick to it we are in with a chance.
"That is all I can ask the boys to do as Morton are the favourites to go through."