An own goal by Southampton defender Alfie Jones was enough to hand a 1-0 victory to Swansea City, who moved top of Group A as a result.
Jones tried to block Adam King's low shot but only managed to divert the ball into his own net at Saints' training centre.
The result means that Swansea top the group on seven points, one ahead of Southampton and three clear of Newcastle United, who have played one match more. Bristol City are bottom with three points, but have only played three matches.
See: Premier League Cup tables
🎥
— Southampton FC (@SouthamptonFC) February 13, 2017
Watch the best of the action from #SaintsFCU23s' #PLCup defeat to #SwansU23s: https://t.co/DVcCHz1B34 pic.twitter.com/Xo5zirRn3S
Both the Swans and Saints play their next group matches against Bristol City (Southampton meet them at Twerton Park this Thursday) while Swansea host them seven days later at their training centre.
The two sides are also in Premier League 2 action next Monday with Southampton facing Everton at Goodison Park and Swansea entertaining Norwich City at their training centre.
See: Southampton report
(Photos courtesy of Matt Watson/Southampton FC)