Scottish sensation Barry Bannan was the star of the show as he capped a fine all-round performance with a super strike.
Bannan's fellow midfielder Chris Herd also netted as the second string showed their senior team mates the way ahead of a Premier League clash with Paul Hart's side on Saturday.
Pompey started well but Claret and Blue summer recruit Andy Marshall was in defiant mood as he parried striker Paris Cowan Hall's effort onto the bar.
Last season's champions Villa then began to set the tone and on 33 minutes they took the lead.
Talent
Bannan picked the ball up on the edge of the Pompey area and finished with aplomb to put his side in control.
The diminutive starlet is really starting to come good and he is bound to be keen on making an impact for the first team sooner rather than later.
Another promising young talent is Aussie Herd and after a spell on loan at Port Vale, he is looking a far more mature player.
His influence in midfield is vital for the reserves and he sealed a third consecutive league win with a cool finish after fine work from Andreas Weimann.
Villa's second string are performing superbly once again and with the first team also tasting success of late, the picture is a pretty one for fans of the Claret and Blue.