Pompey delivered a third successive victory and clean sheet at Walsall.
And Anton Walkes’ influence at the Bescot Stadium was key to the Blues clinching a 1-0 success.
The Tottenham loanee was utilised in a holding-midfield role by Kenny Jackett, with Nathan Thompson reverting to right-back.
Walkes’ principal task was to nullify the attacking threat of Saddlers talisman Erhun Oztumer.
The Turk has netted 15 goals this season but offered little against Pompey and was substituted on 84 minutes.
The diminutive figure was ineffective as Walkes policed him throughout, ensuring he didn’t have the time or space on the ball to dictate the game.
The 21-year-old revealed the game plan Kenny Jackett engineered was specifically to mark Oztumer.
He said: ‘That’s what I was set out to do and I got instructed by the gaffer.
‘The gaffer asked me to step in at the start of the week and as enthusiastic as I am I’m up for any challenge.
‘Obviously, he’s a great player.
‘And he is their top goalscorer with 15 goals this season.
‘You have got to stop someone like that.
‘The gaffer instructed me to keep him in my distance, make sure I was in and around him, tidy things up and don’t make things complicated.
‘He said just keep it simple once I got the ball back and focus on defensive duties.
‘It was thinking a little bit differently. I don’t think they were really expecting it and it changed their game plan.
‘It just changed things around and it clearly worked for us.
‘We’re walking away with three points, a clean sheet and we’re all set for the Wigan game now.
‘Fair play to the gaffer – he knows his stuff and you never know what he’s got up his sleeve.
‘He’s a great coach and everybody puts their trust in him and it paid off.’
For Walkes, it represented a first appearance in the middle of the park since joining Pompey on loan from Spurs until the end of the season.
In his previous 10 outings, he’d operated in a right-back role.
However, he switched positions with Thompson from the Blues’ 3-0 success over Oxford United.
Although Walkes can function in either, he insists he doesn’t have a preference.
‘It was good to give the back four a bit more insurance and make sure we could stay nice and solid,’ he added.
‘Thommo’s preference is full-back and me and him don’t mind swapping around and it paid off.’