Managerless Pompey slumped to a fifth-successive defeat on a miserable afternoon in Bury.
Guy Whittingham and Andy Awford took the reins following Michael Appleton’s departure for Blackpool earlier in the week.
Yet they couldn’t prevent a 2-0 loss in a match the Blues once again struggled to create sufficient goal-scoring opportunities.
Adam Lockwood broke the deadlock on 19 minutes when he looked to have got a touch on Zac Thompson’s shot from outside the area, which was allowed to creep through a crowded penalty area and into the net.
A second was added by Steven Schumacher on 56 minutes from a controversial penalty awarded against Carl Dickinson.
Pompey barely threatened Bury keeper Trevor Carson throughout as they maintained their miserable run.
Whittingham made three changes to the side which lost against Brentford in the week.
In came Ashley Harris, Mikkel Andersen and fit-again Darel Russell, with Simon Eastwood and Adam Webster dropping out.
Also missing was Akos Buzsaky, who injured his hamstring in training on Thursday.
When the match got under way, Harris would have Pompey’s first attempt on goal, volleying a dipping effort comfortably over the bar after a clearing header fell to him 25-yards out.
A piece of quality from Izale McLeod then saw him, with back to goal, touch Lee Williamson’s pass past marker Matt Doherty and swivel to fire a shot narrowly wide.
Yet on 19 minutes the hosts took the lead after poor defending from the Blues.
There were suggestions of a foul on Andersen as a corner came in from the left and the ball fell to Lockwood on the edge of the area.
He beat Harris to it to drive in a shot which someone went through a packed penalty area and trickled in at the far post.
Pompey responded with Dickinson drilling a ball down the left channel to put McLeod through. The striker neatly lifted the ball over one defender only to then half-volley it over.
A great move from the visitors on 30 minutes saw Williamson free Harris down the right and his cut-back found Brian Howard, whose first shot was blocked and his second screwed wide.
Bury were the better side, though, and David Worrall fired in a swerving shot from the left which Andersen did well to collect cleanly.
At half-time Gyepes was replaced by Johnny Ertl in the centre of defence in an enforced change with the Hungarian injured.
Within seconds of the restart, Troy Hewitt found himself clean through but Andersen did well to stand up and block with his feet.
Bury extended their lead on 56 minutes in highly-controversial circumstances.
Dickinson appeared to produce a brilliant sliding tackle on Dominic Poleon inside the box, only for the linesman to shock both sets of players by signalling for a penalty.
There were furious protests from the visitors, but Schumacher stepped up to plant it to Andersen’s right.
Jack Compton and Liam Walker were introduced and the latter curled a left-footed shot from the right which whistled past the far post with keeper Trevor Carson beaten.
But there was no way back for the visitors.
BURY 2 (Lockwood 19, Schumacher 56 - pen)
Bury: Carson, Skarz, Lockwood (Jones 76), Worrall, Shcumacher, Hughes, Hewitt (Bishop 70), Hopper, Doherty, Thompson, Poleon (Jones 84). Subs: Sweeney, Healy, Belford.
Pompey: Andersen, Dumbuya, Gyepes (Ertl 46), Michalik, Dickinson, Williamson, Russell (Walker 65), Howard, Harley (Compton 57), Harris, McLeod. Subs: Eastwood, Webster.
Referee: Craig Pawson (South Yorkshire)