Portsmouth 1-2 Scunthorpe United
Loan signing Dave Syers scored his first two goals for managerless Scunthorpe United, who sent Portsmouth crashing to a fourth successive defeat.
Tom Craddock headed the home side in front from a Ricky Holmes cross.
But Pompey's lead lasted only four minutes, with Syers equalising at the far post after Andy Dawson's corner found its way through the six-yard box.
He later grabbed the winner after keeper Trevor Carson spilled Sam Winnall's left-foot shot into his path.
VIEW FROM THE DRESSING ROOM
Portsmouth manager Guy Whittingham told BBC Radio Solent:
"Defensively you look at us and you think we're not as confident as we are going forward and that's something we have to address.
"We've got two players in at 21 and 23 so they are young defenders and we didn't manage to find that experienced defender. You're going to get times where players are high or low on confidence and at the moment those two aren't in the best of their form.
On upcoming fixtures: "It's good to have one, you don't want to dwell on defeats so it's good to bring the players in and train hard and work towards victory."