Steve Cotterill praised the second-half Elland Road impact of Kanu.
The introduction of the veteran after the interval in a withdrawn striking role, operating just behind Benjani, helped transform Pompey’s performance.
With Bjorn Helge Riise dropping out, it effectively meant four in midfield.
The Blues went on to produce a dominant second 45 minutes, a vast improvement on the opening half.
Regardless, Leeds held on to secure a 1-0 victory, courtesy of Danny Pugh’s 14th-minute header.
With Dave Kitson injured, options were restricted for operating with two strikers from the beginning.
But Cotterill felt Kanu’s arrival and the system switch deserved to reap a point for Pompey.
He said: ‘I wish I’d had King 10 years ago because he would be the first on the team-sheet.
‘He cannot play too many full games and I just knew he would find some space in between the back of their midfield.
‘When the game ends up getting stretched, like it did at the end, that is when he is going to be at his most effective.
‘If you start him there, we are then going to end up changing him for a midfield player and it is not going to have the same desired effect.
‘We ended up going with David Norris and Liam Lawrence in there to begin with.
‘But because of the distances they have done this week, you know they are going to burn out at some stage.
‘Kanu comes on and for sure he gives everybody a lift, he gives everybody that bit of composure.
‘We did enough to get something out of the game, probably only to draw.
‘Not enough to win the game because of our first-half performance.’