Despite three changes from Eric Ramsay at half-time, it was the hosts who once again made the opening stages of the half count – this time midfielder Adams found space to bundle a third home.
Mikey Johnston tested Portsmouth goalkeeper Nicolas Schmid with a curling effort afterwards, but otherwise, the Baggies were left empty-handed on the South Coast.
Albion: O’Leary; Mepham, Phillips (Styles 46’), Taylor; Iling-Junior (Maja 46’), Molumby (Mowatt 73’), Diakité, Imray (Gilchrist 46’); Price, Heggebø, Johnston (Wallace 63’).
Substitutes: Griffiths, Dike, Whitwell, Bostock.