Hibernian were stunned by League 1 Kelty Hearts as Callum Flatman's header defeated the Premiership side in Scottish League Cup Group C.
David Gray's side could not recover from the 58th-minute opener at New Central Park as he sustained his first loss as Hibs head coach, though they remain top of their group.
Aberdeen made it two wins out of two under new head coach Jimmy Thelin, scoring four without reply away to East Kilbride.
Four more Premiership sides, Dundee United, Motherwell, Ross County and St Johnstone, enjoyed wins against Ayr United, Clyde, Raith Rovers and Morton, respectively.
Airdrieonians, Alloa Athletic, Annan Athletic, Falkirk, Hamilton Academical, Inverness Caledonian Thistle, Livingston, Partick Thistle and Peterhead all secured victories.
