Defending champions St Mirren opened their Premier Sports Cup campaign with a dominant 4-0 win over Dumbarton, while Championship side Greenock Morton were stunned at home by Lowland League title holders Linlithgow Rose.
Scottish Cup finalists Dunfermline Athletic were also upset by third-tier East Kilbride.
Dundee fought back to avoid a surprise home defeat to League One Airdrieonians, and Falkirk swept past Edinburgh City.
Dundee United needed a stoppage-time penalty to get past fourth-tier Stirling Albion, while Arbroath, Ayr United, Hamilton Academical, Partick Thistle, Queen’s Park, Raith Rovers, Ross County and Stenhousemuir also recorded wins.