Henri Anier's late goal looked like it had given Dundee United a win over Arbroath, but Colin Hamilton bundled in a dramatic equaliser.
That took it to a shootout in the new group format and Cammy Bell saved from Liam Callaghan to win it for United.
Raith beat Cove 2-1, with Partick Thistle beating Airdrieonians 1-0.
Teams get one point for drawing after 90 minutes, with an extra point awarded to the winner of the shootout.
A man-of-the-match performance from Arbroath goalkeeper Robbie Mutch, on loan from Aberdeen, had denied United for so long.
But, when Cammy Smith's shot deflected into the path of Anier with five minutes to go, he rolled it into the far corner.
However, in stoppage time, Hamilton scored from close range, although it looked like it came off his arm.
Charlie Telfer, Coll Donaldson and Paul Dixon scored for United from the spot, with Steven Doris, Mark Whatley doing likewise for Arbroath.
Bell tipped Callaghan's effort onto the post and, after United's Harry Souttar and Arbroath's Colin Hamilton netted, Scott Fraser stepped up to win it for Ray McKinnon's men.
At Station Park, Cove Rangers took a shock lead through new signing Ryan Stott, but within four minutes, Kyle Benedictus had Raith Rovers level.
Lewis Vaughan ensured a winning start for new manager Gary Locke, finding the winning goal virtue of help from the crossbar.
It means that United and Rovers lead their respective groups with 13 more games coming on Saturday.
History was made in the Scottish League Cup with the first game of its new group format being won on penalties following a 1-1 draw after 90 minutes.