Pompey let a first-half lead slip as they went down to a 2-1 Boxing Day loss to Crawley.
That made it 11 games without a win as the Blues’ struggles continued at Fratton Park.
Paul Benson’s first-effort was cancelled out by Mat Sadler before Billy Clarke got the second-half winner.
And there was the sight of top scorer Izale McLeod on the bench as speculation over his future continued.
Pompey paid for their lack of conviction in the final third during a largely even encounter.
The first-half proved a tale of two crosses in the period’s crucial moments.
Scott Allan’s delivery after 10 minutes looked to get the faintest of touches from Benson as it nestled in the far corner of Paul Jones’ net for the opener.
The visitors levelled 18 minutes later, though, as Jon Harley pulled down Mike Jones and Sadler’s delivery from wide found its way past Simon Eastwood.
Hope Akpan then had a chance for a second but volleyed over before a fine solo run from Muzzy Dumbuya ended with him curling a shot too high before the break.
Benson could have had a second four minutes after the restart as he was put clear by Brian Howard – but Jones saved his low shot.
That proved costly as the Reds went back in front with 17 minutes remaining, as Nicky Adams’ cross was turned in by Clarke.
Pompey had the ball in the net late on through sub Lee Williamson – but referee Roger East spotted an infringement.
And there was time for Jones to pull off a top-drawer stop to deny Darel Russell’s header before the full-time whistle blew.
The defeat leaves Pompey in 21st position on 21 points ahead of the visit from Yeovil on Saturday.