Requiring a 3-0 victory over Crystal Palace Under-21s to qualify for the knock-out stages, George Hirst netted the decisive third goal two minutes into time added on.
It capped an outstanding display from the Leicester City loanee in only his third start for Pompey.
Cowley was also buoyed by the displays of Academy pair Adam Payce and Harvey Hughes on their debuts, while Harry Jewitt-White performed a star turn from the bench.
It marked five games unbeaten for the Blues – and Cowley was afterwards buzzing.
He told The News: ‘It was one of my favourite nights at Fratton Park, a really good performance from the whole squad.
‘I am so pleased for the young players, I thought they acquitted themselves brilliantly well.
‘Young Adam Payce played with such intelligence for a boy, he’s a first-year scholar and only left school three or four months ago.
‘Harvey Hughes defended ever so well, he was really good on the overlaps, there was some good quality with his crossing, and Harry Jewitt-White came on and played like a 25-year-old with a real composure.
‘I’m really pleased for the young players, proud of the senior players for the way they supported the young players, and it was a really positive night for the football club.
‘Football is always about winning, trying to perform well – and winning is a culture we are trying to create here.
‘It’s a habit. I could be playing tiddlywinks against my eight-year-old and I’d want to win, that’s what it has to be.’
While Hirst shone, Gassan Ahadme and Michael Jacobs also impressed after challenged to grab their opportunity.
And they have enhanced their first-team chances considerably following the Crystal Palace triumph.
Cowley added: ‘It was a really good, positive performance and great for the squad, we know that competition drives places.
‘After the Sutton game I knew it would hurt the team. The squad players didn’t play well and the first-team players maybe became a little complacent.
‘It’s really important that there is competition and the whole squad is putting their hand up.’
A message from the Editor, Mark Waldron
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