There were sighs of frustration around Fratton Park when referee Paul Howard blew his whistle to signal an end to the first half.
Pompey had more than 75 per cent of possession against Forest Green, but struggled to break down a team content to get everyone behind the ball.
Owen Dale had faith that the home side would get the job done and the crucial goal duly arrived within six minutes of the restart.
It was the on-loan winger who found the net by heading home a Joe Rafferty delivery and he felt it was a deserved win.
Dale said: “It was a solid team performance against a side whose league position probably doesn’t do them justice.
“We controlled large parts of the game, especially in the first half, and were really dominant in possession.
"Goals always give you confidence and hopefully I can now go on a bit of a run during the final weeks to help the team."
“You have to be patient and we just needed to keep up what we had been doing. We were probing and just didn’t test the keeper enough.
“Luckily we managed to get the goal after the break and it was great play from the lads down the right-hand side.
“The cross has found the back post and I’ve got across the defender and send it towards the goal. I’ve only scored twice for Pompey and they’ve both been headers!
“It was nice to get on the scoresheet, although I think we probably should have had a few more – especially myself – to kill it off.
“Goals always give you confidence and hopefully I can now go on a bit of a run during the final weeks to help the team.
“Overall, I think it’s a performance we can be happy with and now we’ll just move on to the next game.”