That is the verdict of Jan Aage Fjortoft, who believes Pompey represents the perfect stage for the 28-year-old Norwegian to get his football back on track.
Riise has started just five Premier League matches since joining Fulham in a £2m move in the summer of 2009.
He hasn’t featured for the Craven Cottage club in any competition since the season began.
That lack of action has subsequently cost him his place in Norway’s squad.
The midfielder, who has been capped 31 times by his country, has been omitted from their October 11 Euro Championship clash with Cyprus in Oslo.
It is the first time Riise has been axed from the international set-up since breaking through in 2007. Now he has the chance for regular first-team football at Pompey.
Joining on an emergency loan, he made his debut in Tuesday night’s unfortunate defeat to Peterborough.
Compatriot Fjortoft signed him for Lillestrom while serving as their sporting director back in 2005.
And the former Swindon, Middlesbrough and Barnsley striker is convinced Riise will flourish on the south coast.
He said: ‘I know Riise. I’ve worked with him in the past.
‘I took him to Lillestrom from FC Brussels – he was my second signing – and he did very well.
‘He has not played regularly for a long time and this is a timely move for him.
‘He needs this and I am sure he will do well for Portsmouth.
‘He is a player who needs to be on top of his game 24/7.
‘When that happens and he is fully concentrated, he was always one of the best in training.
‘He was very enthusiastic and full of running.
‘He’s a clever boy. He knows what his qualities are and plays on them, which is basically winning the ball and delivering it to people.
‘Riise will work very hard for the team.
‘He has good lungs on him but he will also take people on, he will pass the ball and he is brave.
‘He probably needs confidence at the minute having not played for a while.
‘But when he has that belief in himself he can be a very good player.
‘He is an honest guy, who works very, very hard.
‘And I think he’ll do good things at Portsmouth.’
Riise’s sole international goal came against Bosnia and Herzegovina in 2007.
His only goal in English football came against Saturday’s opponents Leeds while on loan with Sheffield United last season.
And Fjortoft believes that is part of his game which should be more successful.
He added: ‘If I have one criticism of Riise, he does not score enough goals, which he should do.
‘He should be much more effective in that area.
‘If I had a shot like that, I would be speaking fluent Italian as well as German and English!’