Jack Whatmough saluted Pompey's new-found resilience after opening-day victory.
The Blues defender served up a man-of-the-match performance as Kenny Jackett's men delivered a 1-0 success against Luton.
Pompey produced a rearguard action and stood firm as they came under intense pressure from the Hatters.
Whatmough admitted his team would have struggled to see out the game last term when they conceded a number of late goals.
He said: 'The main thing is we came away with a clean sheet and three points on the opening day.
'It's something to build on but it's just a start. Nothing's won today. It's a good platform to build on, though.
'That's probably the case (they wouldn't have held out last season).
'We're a year more experienced under the work of the new management. We're a year more experienced as a team.
'We've had the additions to the team and they have been in this league, done it and played at a higher level.
'We defended well from one to 11 along with all the subs who came on.
'It's not just me, there was the back four plus Craig (MacGillivray) and the two sitters in front of us.
'It's not just one player, it was a whole-team effort to make sure we kept a clean sheet.
'It's good to leave with three points against a Luton team who are a good side.
'It's early in the season, but they are a good side and they won't struggle in this league.
'We've done well as a defensive unit. We showed we're a compact side now and we will ride the storm when it comes.'
Jackett has worked hard over the summer to drill his side into being resilient, with Pompey looking to be a hard unit to break down this season.
Whatmough added: 'Everyone know their roles and responsibilities to keep clean sheets.
'We will get goals with the attacking threat we have.
'It's our job to keep a clean sheet and then let the forwards get goals.
'We didn't have the ball as much as we'd have liked, but we defended really well and that was the main thing.
'We had to be solid and we're coming away happy.
'We have to build on this now and start again this week building towards Blackpool.
'Thommo's (Thompson's) header in the first half (to deny Collins a certain goal) summed it up.
'We were putting bodies on the line and that's exactly what he's done there. That's stuff we need.
'It's part and parcel of being a defender putting your head and body on the line. You have to put your head and body where it hurts.
'Coming away with three points and a clean sheet like that, you can't argue.
'To a man we were brilliant defensively.'