Pompey were trailing by two goals to a side who were on course to be named League One champions.
Yet Danny Cowley remained confident that his side could turn things around against high-flying Wigan at Fratton Park.
And that is exactly what happened, as the Latics failed to build on first half efforts from Callum Lang and Will Keane.
George Hirst grabbed a quickfire brace after the interval before Aiden O’Brien came off the bench to grab a late winner.
It was a deserved outcome for the hosts and Cowley was delighted with the way they fought back to triumph.
The Blues boss said: “It was a really great night and an absolutely brilliant way for us to finish our home season.
“We were so disappointed to go in 2-0 down at the break because I thought we’d played well in the first half.
“The opener saw us lose the ball in our own half, but then Connor Ogilvie had a brilliant chance to level just before we conceded another soft goal.
"There’s a lot of fight and spirit in this group and we’ve come a long way together – this was a great challenge for us."
“We knew we’d done a lot right and just had a couple of poor moments, so couldn’t afford to let that knock us off our tracks.
“There’s a lot of fight and spirit in this group and we’ve come a long way together – this was a great challenge for us.
“We needed to show that and knew that if we got one goal, we’d get another, while you can’t underestimate the role the supporters played. Wow, how powerful was that.
“They stayed with the group and the best moment was at 2-0 down when they kept on our side and gave us confidence.
“We scored three really good goals, as well as showing determination and spirit, which is what our fans want. They want to see the players fighting for the badge.
“It was a really good win for us and there’s connection building here at Fratton Park – we’re showing it can be a fortress.
“This match was about having pride on our performance and we wanted to show energy, intensity and enthusiasm.”