Swansea City reached the last 16 after beating Bristol City 4-0 at Ashton Gate.
Needing a victory to overtake Southampton for the second of two qualification spots from Group A, Oli McBurnie opened the scoring with a volley on the half-hour mark.
George Byers tapped in from a Daniel James soon after half-time, McBurnie netted his second goal from the penalty spot and Jordan Garrick added a fourth in stoppage time.
The result means Swansea join Group A winners Newcastle United in Friday’s knockout stages draw, which will be tweeted live on @PLYouth from 12pm. Bristol City finished fourth in their debut PL Cup campaign.
Swansea could clinch the Premier League 2 Division 2 title in their next match, a home encounter with Wolverhampton Wanderers at the Liberty Stadium on Monday 13 March.