Pompey found a ruthless streak to see off Northampton and climb into the play-off places.
Chris Long had fired the struggling visitors ahead, only for Matty Kennedy’s strike and an Oli Hawkins’ brace to turn the match on its head.
It was ultimately a comfortable victory for the Blues, who went on to create a host of other scoring chances.
And Joe Gallen was delighted with how potent they looked at Fratton Park after recovering from a first half setback.
Pompey’s assistant manager said: “It wasn’t comfortable when we went one down, but to come back as strongly as we did was impressive.
“I still believe that we were the better side in the first half, even if Northampton made it hard for us to break them down.
"We need lots of quality and I’m pleased to say we had that in abundance."
“We needed something and were wondering where that was going to come from, then Matty popped up with a really good strike into the bottom corner.
“That got us back into the game and from that point on it just seemed like we were creating chance after chance.
“Oli scored a terrific header from a great diagonal pass by Christian Burgess and there were numerous more opportunities after he had added the third.
“People will look at our home form and try to stifle us, so we need lots of quality and I’m pleased to say we had that in abundance.”
It was not all good news for Pompey, though, with Danny Rose going off after being kicked during a drop-ball and Gareth Evans also picking up an injury.
Gallen explained: “Danny went to the hospital to have an x-ray and get confirmation, but the opinion of the physio is that it’s likely to be a fracture.
“That’s a huge disappointment for him and for the team because he’s performed very well in recent weeks.
“Having had a couple of fractures myself, though, it is definitely something that you can come back from reasonably quickly. It just depends how bad it is.
“We spoke to the referee about it because we had clear possession when he blew his whistle and normally the other team would kick it back to you.
“I haven’t seen it again, but I thought it was a pretty clumsy challenge from their player. It’s frustrating that it happened.
“Gareth went off with an injured hamstring, which is normal enough when you have so many games in a short space of time.”