Many fans, including myself arrived at the ground late due to traffic congestion and poor weather conditions only to find that Portsmouth were already a goal down courtesy of Craig Beattie's strike.
Swansea were all over Pompey like a rash by the time the majority of the visiting fans had taken their seats. Jamie Ashdown had to make a couple of saves from Darren Pratley and the home side's wingers were causing Pompey's full backs plenty of problems.
Dave Kitson had the ball in the back of the net on 16 minutes but the goal was disallowed for Liam Lawrence's handball in the build up and there may have been an offside decision in the incident too.
But it was Brendan Rodger's side who had the superior movement and creativity and again Pratley tested Ashdown before Nathan Dyer slotted the ball agonisingly wide after the onrushing Pompey 'keeper provided him with an empty net to score in.
Dave Kitson wasted a great opportunity to pinch an equaliser five minutes before the break by heading over John Utaka's cross but the goal did come just a minute later.
Utaka, who was playing behind Kitson in a 4-4-1-1 formation, provided a perfect through pass for Nugent to run on to and slot the ball past Dorus De Vries to give Pompey an undeserved equaliser on balance of play going into the break.
However, that goal seemed to change the way Pompey played as Steve Cotterill's men came out for the second half looking like a completely different team.
Portsmouth were transformed from a team who were being dominated into a team who controlled the game and kept the ball much better than the opposition who were now cheaply giving it away.
And the difference was clearly conveyed when Pompey took the lead thanks to a cleverly worked set-piece aided by some poor defending from the home side.
Lawrence whipped the ball into the box that was met by an unmarked Greg Halford who headed in his second goal for the club which sent the travelling Pompey fans into raptures.
A Swansea surge was expected but the Pompey defence tightened up and dealt with incoming crosses from the flanks, meaning the frustrated hosts resorted to long range efforts that never troubled Ashdown.
Pompey were disciplined in holding their lead and the reward was a morale boosting victory that not many people saw coming, yet had been earned in the second half.
Perhaps the performance after the break will prove to be a turning point in our season. The defence looked as composed as they have been all season and the belief looks to have returned after four games without a win.
Make no mistake about it, to come to Swansea and win is no easy feat so this may arguably be our best result so far this season. It's certainly by far and away our best result on the road this campaign and will be unless we can win at Loftus Road or the Cardiff City Stadium.
We now need to build on this result with a win against an out-of-sorts Burnley at Fratton Park next week because the next two trips to Norwich and Leeds will be just as difficult as last night's game.
But after that result, the belief will be that we can take points from those games.
Pompey Player Ratings
Jamie Ashdown: 6 - May have done better with the opening goal but redeemed himself with some good saves.
Greg Halford: 7 - Proved he can be a threat in the air and was much better at the back too.
Aaron Mokoena: 7 - Much improved performance.
Ricardo Rocha: 7 - Always there to make a last ditch tackle or clearance.
Joel Ward: 6 - Shaky first half but improved after the break.
Liam Lawrence: 7 - Getting back to his best.
Hayden Mullins: 7 - Put himself about.
Michael Brown: 6 - Solid showing.
David Nugent: 7 - Scored but didn't do much else in truth.
John Utaka: 7 - Playing him off the lone frontman worked well.
Dave Kitson: 6 - Guilty of a glaring miss but always worked hard.
Substitutes
Darryl Flahavan
Ibrahima Sonko
Hermann Hreidarsson (Kitson 90): N/A - Late cameo playing as a bustling centre forward!
Richard Hughes (Brown 78): N/A - Settled into the game fine.
Nadir Ciftci (Utaka 90): N/A - Time wasting switch.
Kanu