Stevie Mallan's winner against Queen of the South lifts St Mirren into seventh place in the Championship.
Iain Russell helps maintain Queen of the South's Championship play-off push with the only goal against Alloa.
Rangers midfielder Andy Murdoch joins Queen of the South on loan at the end of his spell with Cowdenbeath.
A double from stand-in skipper Garry Fleming was enough for Dumbarton to prevail in a tight clash with their Championship rivals, Fleming scoring on either side of a Derek Lyle goal to earn the home side a deserved place in tomorrow’s fifth-round draw.
A Garry Fleming double sends Dumbarton through to the Scottish Cup fifth round at the expense of Queen of the South.
With Queen of the South facing Division Two side Cowdenbeath in the Tennent's Scottish Cup Fourth Round on Saturday, Vital QOS will take fans a tour around Central Park and beyond.
Queen of the South have captured the signing of Hearts goalkeeper Jamie MacDonald on loan until the end of the season.
Queens have signed striker Stephen Dobbie from St Johnstone. The 24-year-old had been out on loan to Dumbarton and while there scored 11 goals for the Third Division side.