Palace returned from the south coast empty handed after a dogged display saw them overcome by an excellent Pompey side after David Nugent's second half strike.
Dougie Freedman made one change from the side that beat Sheffield United as Sean Scannell came in for Wilfried Zaha after impressing as a substitute and Palace started brightly as Paddy McCarthy headed wide from a corner in the opening five minutes.
It didn't take Portsmouth long to hit their stride though as they got the ball down and, with their strike-force linking well, looked to get the ball forward early and to feet. A dangerous ball in from Jonathan Hogg led to their first chance which Joel Ward nodded just wide, although Julian Speroni was adjudged to have been fouled in the build-up.
Anthony Gardner then had a great chance to give the Eagles the lead as he rose highest to meet a Darren Ambrose corner but headed the ball back across goal when he should have done better.
Pompey soon began to look like the side that had just been relegated from the Premier League with a succession of dangerous attacks. First Gardner doing well for Palace with a sliding challenge as Dave Kitson almost got through on goal, then David Nugent scuffed wide with Pompey playing the ball around on the deck impressively.
The best chance of the half though came from a long throw from Greg Halford which the outstanding David Cotterill just missed at the far post, when any touch would have meant a goal. Nugent then showed his class cutting inside well from a diagonal ball and seeing his shot was blocked by Speroni, the ball fell to Cotterill who should have opened the scoring but blazed over the bar from nine yards.
Palace were weathering the storm well with Paddy McCarthy clearing well after Ritchie De Laet had burst into the box and done well to cut the ball back. Then a lovely passing move that started with a De Laet cruyff-turn ended with David Nugent flashing the ball across goal for the last goalmouth action of the half.
Pompey came again at the start at the start of the second half with Nugent heading wide from a dangerous right-wing cross and then McCarthy clearing well from another dangerous Cotterill delivery. A foul on Scannell at the start of the second half gave Darren Ambrose a chance from a free-kick but his strike hit the wall and Pompey broke through Dave Kitson who was held back just outside the box. Halford stepping up for Pompey and blasting his free-kick past the wall but too close to Speroni who saved well.
Minutes later though Portsmouth were ahead as a long throw from Cotterrill was flicked on by Kitson and fell for Nugent in the box who struck the ball first time, into the ground and over Speroni to give Portsmouth a 1-0 lead. The Eagles were almost level immediately when a Darren Ambrose delivery fell for McCarthy who timed his run perfectly but headed a good chance just wide.
Another Cotterill ball in caused havoc in the area with Speroni just doing enough as Kitson looked well placed to double Portsmouth's advantage as Freedman threw caution to the wind with the introduction of Steffen Iversen, Wilfried Zaha and Jermaine Easter.
Zaha's introduction almost proved vital when he broke free down the left and whipped in a good ball that Halford did well to clear. McCarthy then one Palace a free-kick deep into Pompey territory as the game entered addded time but it came to nothing as Porsmouth held out for all three points.
Portsmouth: Ashdown, Halford. De Laet, Hreidarsson, Mullins, Nugent, Hogg, Cotterill, Kitson, Ward (Mokoena '92), Rocha.
Subs: Flahavan, Dickinson, Ciftci, Kilbey.
Crystal Palace : Speroni, Clyne, Wright, McCarthy, Ambrose, Danns (Zaha '72), Scannell (Easter '72), Vaughan (Iversen '81), Moxey, Gardner, Dikgacoi.
Subs Not Used: Price, Davis, Barrett, Counago.
Att: 15,641 Ref: Mr B Malone