Jermain Defoe scored the winning goal, but also saw red as the team gathered three points with a 2-1 victory at Fratton Park.
Ledley King opened the scoring and Defoe doubled the advantage right on half-time, but Kevin Prince Boateng reduced the deficit and it was a tense finish with 10 men until Michael Brown was also dismissed in the final moment.
Defoe, who was probably fortunate not to be booked in the opening minute for a chopping challenge on Aruna Dindane, ventured forward into space and warmed the hands of David James for the first time moments later. The little hitman perhaps then should have scored from an Aaron Lennon cross following composed promptings from Jermaine Jenas.
Boateng, presented with a Player of the Month award before the game, fizzed in a free-kick that Dindane did not quite get enough of his head on to trouble the restored Heurelho Gomes.
With nine minutes on the clock Tom Huddlestone threaded a superb ball into the path of Defoe and the striker drilled a low shot past James, but off the inside of the post when an opener looked the likely outcome.
Pompey then should have scored when a dash down the left by Tommy Smith resulted in the ball being squared in front of Dindane, who fired over the bar from right in front of goal.
Gomes made a stunning contribution on 25 minutes when the home side were awarded a free-kick following a Jenas foul on Boateng, for which he was cautioned. Younes Kaboul stepped up and thumped in an effort that struck Smith and Gomes somehow reached up and diverted away from goal. A breathtaking save.
With the clock nearing 30 minutes a deep Niko Kranjcar corner led to King rising high above two defenders and steering a header high into the top corner past James, who appeared to be caught in two minds over whether to stay or come for the ball.
Then right on half-time excellent work by Huddlestone and Jenas resulted in the latter gliding into the area and dispatching a precise low cross that Defoe was able to prod a toe at and James was beaten.
The advantage was doubled and Fratton Park was not a happy place, bar one end of the ground at the break.
The second half began with Keane, Defoe and Lennon breaking on two Pompey defenders and it took Kaboul to make up some ground and deny Lennon adding his name to the scoresheet, while there was a spot of confusion between Gomes and Vedran Corluka at the other end that had the home fans screaming for a penalty. Mr Dowd was not swayed.
Jenas was doing sterling work for the team at both ends, making vital blocks, challenges and interceptions at the back, while offering speed and guile going forward. His workrate was making light of the loss of Wilson Palacios.
Peter Crouch was called from the bench on 56 minutes, taking the place of Keane, while giving the home fans someone else to boo, while they might have had something to cheer if the athleticism of Gomes not diverted a Smith lob. Dindane was then guilty of another miss in front of goal after being teed up by Smith.
The deficit was reduced just before the hour when a deep cross found the unmarked Boateng and the ex-Spur smashed low into the net at the near post. Boosted by the goal, Portsmouth then found themselves with a one-man advantage when Defoe was given a straight red card for a tangle with Aaron Mokoena during which he stepped on the former Blackburn player.
To help stem the inevitable tide. Harry Redknapp responded by introducing Wilson Palacios, with Kranjcar making way for the Honduran who had just returned from international duty.
Gomes was forced into another brilliant point blank stop to deny Hassan Yebda, who volleyed goalwards, connecting with a cross from Frederic Piquionne.
Piquionne headed across the face of goal on 84 minutes, before Michael Dawson was drafted in to replace Huddlestone - adding another centre half to the mix.
Lennon could have sealed it when clean through on goal, but slotted wide before Brown was sent off for a second yellow after tripping Lennon on the run.
That knocked the spirit out of Portsmouth and five minutes stoppage time was finally bought to a close.