Leam Richardson praised the impact of Conor Chaplin after he scored twice in the 3-1 victory over Barnet.
The 18-year-old was granted his first league start of the season and responded with a goal in either half at Fratton Park.
Pompey found themselves behind in the 25th minute through Andy Yiadom’s left-foot finish, only for Chaplin to level eight minutes before half-time.
Adam McGurk put the Blues ahead on 55 minutes, before Bees keeper Jamie Stephens was sent off for a second-bookable offence.
Chaplin sealed the result in stoppage-time, marking his fourth goal of the season as Pompey climbed to third in the table.
And assistant manager Richardson was delighted with the youngster’s contribution.
He said: ‘Conor is Conor, I have been here a short while and already you see the lad who loves football and loves scoring goals. His quality, work ethic and endeavour is there to be seen.
‘Scoring goals is a great habit to have and luckily he has got that. Long may that continue.
‘As a team, you are going to have to come up against certain teams and have to fight and defend at times, like you have seen today.
‘When we went behind I thought the lads stuck to their task and I was pleased with the result. You just stick to your beliefs and your work ethic and they got their just rewards.
‘Martin Allen came today and went away from his beliefs, so to speak, by taking a front man off and putting a midfielder in.
‘Fair play to the lads, thankfully we have come through.’