A SWEET strike from Ross Forbes was enough to take Morton through as Queens suffered a second cup exit in a week.
The Greenock side, with Forbes pulling the strings, made the early running but were unable to convert a string of half-chances. Instead the Doonhamers went closest when Derek Lyle’s raking 25-yard free kick clattered Grant Adam’s crossbar.
At the other end Thomas O’Ware saw his glancing header rise just too high.
Morton continued to create the better chances on the restart with Denny Johnstone and Bobby Barr going close.
The home side’s rugged resistance was finally broken on 69 minutes when Forbes gathered a pass from Johnstone and speared a left-footed shot into the bottom corner from 20 yards. Forbes almost sealed Morton’s passage to the next round with a curling free-kick which beat Robbie Thomson only to rebound from a post.
The Cappielow side kept their hosts pegged back and Romario Sabajo forced a good save from Thomson with a snapshot.
Doonhamers boss James Fowler sent on all three substitutes in a bid to salvage the game and one of them, Owen Moxon, forced Adam into action with a shot from the edge of the box.
Adam was in action again to deny Mark Millar as Queens pushed for a late leveller.