Pompey paid the price for their wastefulness in front of goal as they went down to a 1-0 defeat at Ipswich.
Keith Andrews’ 69th-minute strike proved decisive at Portman Road, with the midfielder making the most of substitute Jay Emmanuel-Thomas’ knockdown.
The defeat is the Blues’ fourth on the road this season and their sixth in the league to date, but it could so easily have been back-to-back victories for the managerless visitors.
Pompey had a host of chances in the first half, most notably Luke Varney, who failed to make the most of David Norris’ perfect through ball as he shot straight at Town keeper David Stockdale.
That followed a Hayden Mullins drive that sailed over the bar on 12 minutes after good link-up play between Kitson and Varney.
And it led to a confident-looking Pompey frustrating the home crowd, with Kitson shooting just wide from Liam Lawrence’s corner and Ricard Rocha and Joel Ward tamely heading goalwards when well positioned.
The best the Tractor Boys could do in response was an Andrews shot that was well saved by Pompey keeper Stephen Henderson on 36 minutes.
Pompey again looked the side most likely to break the deadlock in the second half, with Lawrence missing the easiest of chances at the back post a minute after the restart.
Kitson was then foiled as the ball dropped to him in the six-yard box before Norris fired wide from the edge of the box.
The longer Pompey continued to prove wasteful in front of goal, the more Ipswich grew in confidence themselves moving forward.
And they made the Blues pay on 69 minutes when Andrews fired past Henderson from five yards out.
Pompey immediately threw on Kanu and Erik Huseklepp for Kitson and Rocha, with Aaron Mokoena then coming on for Lawence as the home side remained on top.
The triple substitution failed to change Pompey’s luck, with Varney missing from close range after Stockdale had come off his line.
The Blues put up a brave fight in the dying minutes, with Norris’ header testing Stockdale, but they were unable to break through the Ipswich rearguard, leaving the home side to celebrate victory.