The diminutive Ivorian was the hero in midweek after notching a 95th minute equaliser against Sunderland in the Premier League.
And he was at it again at St Mary's after putting Pompey ahead just when Southampton had got themselves level.
Quincy Owusu-Abeyie's first goal in a Portsmouth shirt put them ahead before Rickie Lambert's 25th of the season levelled proceedings.
Dindane's seventh of the season made it 2-1 before Nadir Belhadj and Jamie O'Hara put the game beyond doubt.
Southampton edged the opening skirmishes and wasted a golden opportunity to take the lead after ten minutes when Senegalese frontman Papa Waigo's brought a great one-handed save from David James.
Pompey's first sight of goal came four minutes later when O'Hara curled a 20-yard free kick wide.
O'Hara was at it again after 22 minutes with a stinging left-footed effort but Kelvin Davis turned the effort over the bar.
Lambert was again causing problems 20 minutes after the break, flicking a header into the path of Adam Lallana but the midfielder scuffed a left-footed shot straight at James.
The tie looked to be heading Pompey's way when Owusu-Abeyie picked up a Dindane pass and calmly curled past Davis.
However Lambert had other ideas and put the Saints level after 70 minutes after rising highest to meet Dan Harding's left-footed free-kick.
Just when the home fans were calling for a grandstand finish, Dindane capped off a great week by calmly placing Owusu-Abeyie's throughball beyond Davis.
The Saints thought they were back in it ten minutes from time when new signing Lee Barnard had the ball in the net but the former Southend frontman was offside.
Pompey ensured the win was theirs eight minutes from time when Belhadj raced 50 yards before calmly slotting past Davis.
And man of the match O'Hara put the icing on the cake of the victory with a well struck half-volley on 85 minutes.