Steve Cotterill has urged Dave Kitson to maintain his improved work-rate and reap the rewards.
The striker struck in the second half against Reading on Tuesday night to give Pompey their first win in 12 matches.
It was also his first goal since netting a consolation in a 2-1 defeat at Bristol City in March.
Kitson’s contribution could not have been more timely, with Benjani Mwaruwari arriving.
Fellow forward Erik Huseklepp is also completing a £1.5m move to Fratton Park to provide competition for places.
Cotterill believes Kitson’s work-rate has let him down in the past.
But against Reading he feels the 31-year-old was on top of his game. And he has called for more of the same from the striker who still needs to convince fans.
Cotterill said: ‘Kits is quite a casual finisher and has that loping stride, so sometimes it looks as though he doesn’t work hard.
‘And do you know what – sometimes he doesn’t work hard enough.
‘We have spoken about that.
‘I then felt from missing the chance against Adam Federici in the first half, he ended up then playing outside the box.
‘At half-time I had a quiet word with him and said “I don’t care how many you miss, you have got to keep getting in there”. You have got to keep getting into the box, you have got to be there to score some goals.
‘You might miss a few but, to be fair to him, he got that goal in the second half.
‘I thought he was worth a goal. I thought he worked hard and he has got to keep working hard.
‘That is the one thing our fans don’t accept but it’s the minimum requirement, that is what we ask.
‘And now he has a bit of competition.’
Kitson has scored nine goals in 41 Pompey games since joining from Stoke last season.