An early brace from Sean Longstaff put Newcastle into a commanding lead early on before a Che Adams strike reduced the deficit for Southampton to 2-1 on the night and 3-1 on aggregate going in at half-time.
It was the first goal Nick Pope had conceded in 11 matches to set up a slightly nervous second half at St James’s Park for The Magpies.
A late sending off for Bruno Guimaraes following a VAR check made things even more nervous for the hosts in the closing stages but they kept their two-goal advantage intact.
Here are the Newcastle United player ratings from the match...
1. Nick Pope - 7
Will have been disappointed to be beaten for the first time in 11 matches. Made a huge save to deny Adam Armstrong one-on-one in the second half. | Getty Images
2. Kieran Trippier - 7
A clever pass set-up Longstaff for the opener. Good on the ball and kept things tight defensively. | Getty Images
3. Fabian Schar - 7
Some lovely touches playing the ball out from the back. Hit a free-kick at the wall in the second half and headed an opportunity over in the first. | AFP via Getty Images
4. Sven Botman - 7
Dominated in the air and let little past him on the ground. | AFP via Getty Images