Gareth Ainsworth marked his 250th game in management with a 100th victory as Wycombe edged past Pompey.
Scott Kashket grabbed the only goal of the match on 48 minutes with a heavily-deflected shot from 20-yards to wrong-foot David Forde.
It represented the striker’s 15th goal in 21 appearances as the Chairboys maintained their impressive recent run,
Sitting sixth in League Two and in midweek hosting Coventry in the Checkatrade Trophy semi-finals, Ainsworth continues to impress at Adams Park.
Saturday was a tight contest, yet one the hosts managed to secure another victory.
And Ainsworth is delighted with their ongoing progress.
He told the Bucks Free Press: ‘The discipline was excellent from the boys. We set up a certain way and we executed it really well.
‘We had to find a way of limiting what Portsmouth can do on the ball as they have some good players and we countered them.
‘This was a big result for us and I am really proud of the boys.
‘Some of them were on empty again. I thought Dominic Gape was outstanding once again and the energies of the guys in front of the back four was really good.
‘I didn’t know about the winning landmark, but it really is great. As a manager, it is nice to have these milestones.
‘As a manager, you wake up every day, feeling lucky and happy and I will give everything that day no matter what and my players do the same which is great to see.’
Now Wycombe must focus on Tuesday’s cup visit of Coventry.
Ainsworth added: ‘For any manager, the chance to get to play in a semi-final is awesome.
‘The boys have worked really hard. We will give it our all against a League One side and it will be a great trip for the town.
‘They will give a right go and these boys will achieve one day.’