A depleted Kilmarnock were defeated 3-0 by Championship side Dunfermline Athletic, who now top their Scottish League Cup group.
Hibernian captain David Gray scored a late winner against third-tier Forfar Athletic.
Ross County avoided shock defeat to Arbroath after coming back to win 2-1 thanks to a Ross Stewart brace.
Ryan Edwards scored the only goal of the game as Dundee United saw off Barry Ferguson's Kelty Hearts.
Following an outbreak of Covid-19 at the club, Kilmarnock started with five players from their youth level - with Gary Dicker, Chris Burke, Nicke Kabamba, Rory McKenzie, Brandon Haunstrup and Colin Doyle the senior players allowed to return from a period of isolation. Dunfermline were clinical in the second half, with a Fraser Murray brace and a Euan Murray header sending the Championship side to the top of Group E.
Killie now sit bottom of that group after the 3-0 defeat, with Falkirk second after goals from Aidan Keena and Callumn Morrison in a 2-1 win over Clyde.
Hibernian were held until the 87th minute an obdurate Forfar, but a late David Gray header from a Stephen Mallan delivery sealed a third successive win in the competition for Jack Ross's side, leaving them at the top of Group B.
Cove Rangers had to settle for a bonus point win against Brora Rangers, winning 3-2 on penalties after a 2-2 draw in regular time.
A header and a penalty from Ross Stewart rescued all three points for Ross County in a 2-1 win, after finding themselves behind against Arbroath at home following a cracking strike from Dale Hilson.
Elgin City sit top of Group D after goals from Conor O'Keefe and Josh Peters saw off Montrose 2-0.
Dundee United earned a slender 1-0 win over Lowland League side Kelty Hearts through Ryan Edwards' header, from a Peter Pawlett cross in first-half stoppage time.
United sit behind St Johnstone on goal difference in Group C, while Peterhead beat Brechin City 3-1.
Craig Wighton scored a hat-trick, including two penalties, to secure all three points for Hearts in a 3-1 win over Raith Rovers.
They sit top of Group A with three wins from three, while Inverness Caledonian Thistle had to settle for a bonus point win against Cowdenbeath after being held to a goalless draw in regular time. They won 4-2 on penalties.
There was incredible drama in the penalty shootout at Stranraer after a 2-2 draw, with visitors Albion Rovers winning 15-14 on penalties - scoring 15 consecutive penalties to do so.
Ayr United top Group F after a first-half penalty from Michael Moffat secured a 1-0 win over Annan Athletic.
Ten-man Partick Thistle won 3-2 on penalties after a goalless draw with Queen of the South to take two points from their trip to Dumfries.
In the other Group G game, Greenock Morton saw off Queen's Park with a 1-0 win thanks to a Cameron Blues strike.
Stefan Scougall and Robert Thomson goals helped Alloa Athletic beat Edinburgh City 2-1 in Group H, while Airdrionians saw off Stenhousemuir 2-0 with Craig Thomson and Paul McKay efforts.