Murray fielded a team with five players aged 21 and under, two of them teenagers, but they were on the back foot from the start after Ritchie Sutton was sent off as last man for a foul on Jed Wallace as he tried to finish from Matt Tubbs’ square pass.
Tubbs bagged the spot-kick with two minutes on the watch, and when a nasty bounce from Wallace’s 30-yard shot caught out diving keeper Lenny Pidgeley on 55 minutes, the game looked won.
However, man of the match Jack Thomas bagged his first goal for the club – a 67th-minute beauty – to mark a day in which he picked up four Player of the Season awards.
It wasn’t enough to stop Pompey celebrating their first ever league win over Mansfield, but Murray said: “All credit to the young boys, they were superb. Today was about certain things and I got what I wanted.
“The young ones couldn’t have done any more. Our average age today was under 23.
“They are going to make mistakes. That’s always going to happen. But they are mistakes made in trying to do the right thing.
“It was a great experience for them. It was another ridiculous performance from Jack Thomas. For Joe Fitzpatrick on his debut to be dropped into centre half after 45 seconds, it was daunting enough to be playing his own position, so to go out there and do a job like that was superb.
“I said to Jack before the game that he was due a goal after all his good performances. Then he scored the goal of the season in the last home game of the season.
“He should be an inspiration to everyone. He is on a different level and we should be proud of our football club to have someone like that.
“We all want to put this season in the past as quickly as we can. It’s been a long journey. But today was a spark of what’s to come.
“The planning has already started for next season. I know what we need to do and, along with the fans, I don’t want to go through this again. I don’t want to have to suffer this pain again.
“I am more than confident I can build a competitive side. Don’t get me wrong, there will be a hell of a lot of changes in the summer.
“Yes, we have a core of good, young lads. But you can’t heap all the pressure on them. We will bring in a lot of new faces to help them.”
On the game he said: “It summed up our season didn’t it? It was the perfect picture of our season in one game. It was our whole season in 90 minutes.
“We had enough chances to win it with 10 men but we came up short. In the changing room we have killed ourselves again.”
Sutton picked up three Player of the Season awards minutes before he was sent off and Murray added: “You couldn’t write the script. To be honest it was a tricky one to see where we are. I heard it was a bit harsh, but he shouldn’t have got into that situation.”
After Tubbs had sent Pidgeley the wrong way with the spot kick, the visitors controlled the game, made use of the extra man and Pidgeley had to make a good save to deny Craig Westcarr.
Rakish Bingham had three efforts for the home side, only one forcing Paul Jones to save from close range.
Wallace then doubled the advantage before Thomas curled a superb 20-yard effort from the left under the far angle.
But Pompey clung on for their first away win in seven trips and caretaker boss Gary Waddock said: “A win’s a win and it’s great to get one away from home.
“It was something for the fans to go home with. We played extremely well in the first half and controlled it.
“We identified an area where we could get at them and it worked straight away with the penalty.
“I was pleased with the first half, but we made it harder for ourselves in the second half. We have told the lads they need to manage a game better.
“In the final third we didn’t take enough care when we were in possession.
“With the amount of possession we had we didn’t create enough chances. That was the one disappointing thing.
“We had chances to kill the game off and didn’t take them. We have to be ruthless when those chances come up. If we had, it would have been a lot more comfortable towards the final whistle.”