Partick Thistle were given a fright from Second Division Stirling Albion before securing a narrow cup victory.
Albion's Martin Grehan put two headers wide before Thistle's Scott Chaplin drove home following Simon Donnelly's flick-on from a Ryan McStay corner.
Gary Harkins converted a penalty for the Jags but Craig Molloy netted a loose ball to reduce the deficit.
Liam Buchanan headed home Thistle's third but Albion set up a tense last few minutes with Paul Murphy's goal.
Stirling Albion: Christie, Lawrie, Lowing (Waddell 77), Graham (Ross 46), Gibb, Molloy, Corr (Hamilton 70), Murphy, Grehan, McKenna, Docherty. Subs Not Used: Devine, Hogarth.
Booked: Lowing, Gibb, Murphy, Grehan.
Goals: Molloy 55, Murphy 89.
Partick Thistle: Jonathan Tuffey, Paton, McKinlay, McStay (Turner 60), Archibald (MacBeth 82), Maxwell, Chaplain, Rowson, Buchanan, Donnelly (Roberts 70), Harkins. Subs Not Used: Michael Robertson, Hinchcliffe.
Booked: Roberts, Jonathan Tuffey.
Goals: Chaplain 28, Harkins 33 pen, Buchanan 83.
Att: 1,472
Ref: C Richmond