A double whammy within ten minutes of the start of the second half sent Premiership Portsmouth through to the quarter-finals of the Carling Cup.
Dangerman Yakubu was on hand to open the scoring in the 47th minute and he added a second from the spot eight minutes later.
The Bluebirds were forced to make two changes with Tony Vidmar replacing the cup-tied Darren Williams and Willie Boland taking over in midfield from Gary O'Neil.
Harry Redknapp paid City the compliment of putting out a strong side packed with Premiership experience.
Their front two of Lomano LuaLua and Yakubu had the home defence stretched from the start and a shot from LuaLua skimmed across the face of Tony Warner's goal before drifting wide.
City's first strike on target came midway through the half when a long ball from James Collins was headed into the path of Paul Parry, but his was shot was safely gathered by Jamie Ashdown.
The Bluebirds had settled well and in the 28th minute a snap-shot from Alan Lee forced Ashdown to his knees to save and two minutes later Boland raced through the middle, but David Unsworth deflected the ball for a fruitless corner.
LuaLua and Yakubu were dangerous when Portsmouth broke away and the former Newcastle striker flashed in a shot that had Warner scampering across the goal-line.
Pompey took just two minutes of the second half to take the lead. LuaLua beat Collins down the right flank and his cross was pushed on to the bar by Warner but Yakubu was on the spot to knock the loose ball home.
Portsmouth went further ahead in the 55th minute with the award of a penalty. Graham Kavanagh went into block Matthew Taylor and an outrageous dive from the visitors' midfielder resulted in the referee pointing to the spot. Yakubu coolly put away the penalty to Warner's left.
With the game now safe Portsmouth could relax and play the ball about and the Bluebirds were left relying on occasional breakaways.
Alan Lee sent a header flying over the bar from a Parry cross, but the Bluebirds ended up living off scraps as Pompey closed the game down.