United's youngsters suffered a 5-1 defeat at Southampton.
The Saints took the lead in the 23rd minute when Tadanari Lee converted from close range.
Their advantage was soon doubled when Sam Hoskins rifled home from distance just four minutes later.
Promising teenage striker Adam Campbell (pictured right) replaced Dennis Knight just after the half hour mark, but United went in at the break trailing by two goals despite enjoying some good possession.
And, just one minute after the restart, the Saints went further ahead when Ben Reeves netted with a rising shot from 12 yards after the visitors had failed to clear their lines.
Campbell managed to get one back for the Magpies in the 53rd minute when his shot from distance found the back of the net thanks to a sizeable deflection.
Hopes of a comeback were dashed eight minutes later when Hoskins turned his marker on the edge of the box and drew Jak Alnwick before firing past the goalkeeper.
Reeves then got his second and Southampton’s fifth in the final minute to complete the rout.
NEWCASTLE UNITED: Alnwick, Logan, Riley, Miele, Kitchen, Good, Maddison, Knight (Campbell 31), Hooper, Abeid, Amalfitano.
Subs not used: Mitchell, Gilliead, Desmond