Barnsley boss Mark Robins was left disappointed after his side slipped to defeat at Fratton Park.
The Tykes boss was particularly gutted by the way in which Pompey scored.
Although he reckoned referee Roger East was harsh in the award of a free-kick for the challenge on Aaron Mokoena, it was the defending which allowed Kanu to nod home that most annoyed him.
Robins said: ‘To concede the goal we did in the manner we did was poor.
‘I was shouting on from the side because I could see what was coming. It was a poor goal to give away.
‘A point down here would have been a decent point and set us up for tomorrow night’s game (at Leeds).
‘The free-kick that resulted in the goal was a little bit harsh, I think, but we haven’t defended properly.
‘We conceded a goal late on and left a difficult way back.’
Robins admitted his team were devoid of attacking verve and claimed they lacked confidence in their ability to score.
He said: ‘We threw bodies forward but we lacked ideas up front.
‘We didn’t look like we were going to score a goal.
‘It’s about the players understanding what’s required of them when they go on to a football field.
‘They need to get it into the tight areas and give the team a lift.
‘We need to score a goal away from home earlier, which gives us a little confidence and something to build on.
‘It looked as if we were just hoping we might get a goal, rather than going out and making it happen.
‘That, for me, has been symbolic of the season away from home.
‘We need someone to get hold of the game by the scruff of the neck and make things happen for the team.’