Danny Cowley’s men kept up their 100 per cent start to the league campaign with a hard-earned 1-0 success over Shrewsbury tonight.
Tunnicliffe continued his outstanding start to the season as he grabbed his maiden Blues goal.
His side were forced back late on by Steve Cotterill’s side, who pummelled the home side’s box with crosses and balls into the box.
That was the case after the fourth official indicated eight minutes of stoppage time following injuries after the break.
That continued into 11 minutes but Pompey held on, with Tunnicliffe pleased to see the attitude on display from his new side.
Tunnicliffe said: ‘That was a tough game but we dug in.
‘We dug in at Fleetwood, but I felt we really dug in tonight and showed that we can win ugly.
‘On Saturday we were good and the football flowed, but tonight we showed a different side to our game and dug in.
‘Their front players were a handful for us but the boys at the back really handled that well for us and I think they won the game for us in the end.’
A high defensive line was on display from Pompey for much of the night, with keeper Gavin Bazunu camped outside his box getting moves started.
The home side did well resist the temptation to fall too deep until late on, when the back line showed their resolve to see out the game and collect a third clean sheet on the spin.
Tunnicliffe added: ‘It’s tempting to fall back but the more you go back the more it can create problems, if they win knockdowns.
‘If you drop deeper and they win headers they’ve got 10-yard finishes.
‘So we try to be brave.
‘The gaffer tells us to be brave and the boys at the back try to keep us high.
‘It’s about being brave and not dropping deeper and deeper to give them more of an opportunity than what they already could have.’