Airdrie United new arrivals Andy Ferguson and Gary Mackay-Steven but fellow new boy Adam Fairweather was not signed before the cut-off date.
Captain Paul Lovering is free of suspension and can feature.
Morton manager Allan Moore: "We had a good win against Cowdenbeath at the weekend but Airdrie are not going to come here and lie down so we have to go out and win the game.
"We know the prize in the next round is a trip to Inverness and I am determined that it is us who are making the trip north."
Airdrie United manager Jimmy Boyle: "Andy [Ferguson] is a bit behind the rest of the lads when it comes to fitness, however Saturday's 45 minutes did him the world of good."
Source: BBC Sport