Chaplin struck in the 94th minute to seal Pompey’s first win of 2018 with a dramatic 2-1 success at Stadium MK.
That sparked jubilant scenes as the 21-year-old sprinted the length of the pitch to celebrate with the 6,257 travelling blue army.
Chaplin admitted the reaction was a release of the pent-up frustration which has been building at a lack of playing time.
The outing came after just one minute of action in the previous five league games for the fans’ favourite - leading to his first goal since November.
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Chaplin said: ‘That meant a lot.
‘There were a lot of fans here and I haven’t been playing. It’s been six games so it means a lot and there’s a lot of relief.
‘It was all the feelings coming to the surface, it definitely was. I’m not going to lie. I’m the sort of character who wants to play.
‘I love footie and I just want to play, train and score goals.
‘I’m thankful for the opportunity to come in where I haven’t recently.
‘I showed what I can do and I’m happy to do that.’
Chaplin explained his lack of playing time has been a test of his character.
Now he’s hoping he will get his chance to pick up the minutes on the pitch which have been in short supply.
Chaplin said: ‘It is tough at times, but I think I could be injured or not have the opportunity to be out there training with the boys.
‘That would be a whole lot worse, I know that for a fact.
‘On the other side of it I do feel that if you keep working and believing you’ll get your reward. You can create your own luck by working hard and I won’t shy away from doing that.
‘Everyone wants to play but I enjoy football too much to show a bad attitude.
‘I can’t come into training, be stroppy and not want to train. It’s even more important when I’m out of the team.
‘I couldn’t go the other way, but now I’d hope to get a chance.’
Chaplin explained his lung-busting celebration was also fuelled by a bet he placed with fellow sub Jamal Lowe.
He said: ‘If there was longer left to play we’d have been down to 10 men, because I would have been on the side of the pitch getting my breath back!
‘I had a bet with Jamal before the game.
‘We knew if we came on and scored in the second half we wouldn’t be in front of our travelling fans.
‘There were so many of them we knew we wanted to be in front of them.
‘So we said we’d have to run the length of the pitch - and if we didn’t we’d be paying the other person some money!
‘It’s unbelievable when they are in that kind of voice and in those numbers - I couldn’t not do that. They travel in huge numbers. Hopefully I was able to send them home with a smile on their faces.’