Pompey were under the cosh against a Shrewsbury side that are fighting for their lives to survive in League One.
So Kenny Jackett switched around his attacking midfield trio midway through the first half and it appeared to have the desired effect.
The south coast visitors went on to secure all three points following goals either side of the break from Ben Close and Brett Pitman.
Jackett knew that he had to change things to get his side back on track and was pleased with the response from his players.
The Blues boss said: “It was hard-fought and the first 25 minutes really did belong to Shrewsbury, with our keeper making one outstanding save in that period.
“I was wondering if it was going to be our day, but we changed things a bit tactically and had a lot of chances.
“We weren’t able to provide enough support up to Omar Bogle and it meant he couldn’t quite get into the game.
"I was wondering if it was going to be our day, but we changed things a bit tactically and had a lot of chances."
“So we needed to get Brett slightly closer to the second ball and Jamal over to his natural side, where he could be more of a threat.
“We battled very well from that and looked like scoring goals on the break, which ultimately proved to be the case.
“We got ourselves the first goal – which is always key – and then an excellent reverse ball from Oli Hawkins allowed Pitman to wrap things up.
“Oli came on and hit the bar, forced their keeper into a very good save and then made the key assist for Brett to put the game to bed.”
The result saw Pompey climb above Sunderland and into third position, although Luton and Barnsley – who currently occupy the automatic promotion places – also won.
Jackett said: “We’re trying to keep pressure on the top two and then after that it’s third and fourth spot, which gets you at home in the second leg of the play-offs.
“Beyond that it’s about the gap to seventh to cement a place in the play-offs – they’re all the things that go through your mind.
“You have to find different ways of winning games throughout the season because at the moment there’s no side with nothing to play for.”