And yet again set-piece problems proved costly, with three goals coming from corners and another involving a quick free-kick in the build up as Arsenal capitalised in style.
Colby Bishop opened the scoring on three minutes after Conor Chaplin’s shot had been saved, but Arsenal soon roared back with an Andre Dozzell own goal following a corner.
Gabriel Martinelli added another, then missed from a few yards and then Noni Madueke missed a penalty in a lively first half which finished 2-1.
However, Arsenal controlled the game after the break, with Martinelli completing his hat-trick, while Harvey Blair and Franco Umeh both went off with fresh injuries.
And here are our Pompey player ratings...
6 / 6