Hermann Hreidarsson admitted Sheffield United had provided the toughest test during Pompey’s six-match winning streak.
The veteran settled the Fratton Park fixture with a 24th-minute finish from close range.
That made it six triumphs in a row for Steve Cotterill’s resurgent side, building on victories over Doncaster, Barnsley, Crystal Palace, Ipswich and Scunthorpe.
Micky Adams’ strugglers had their moments, though, pegging back the Blues in the second half.
Regardless, the defence stood firm.
But Hreidarsson believes the Blades asked the biggest questions of all the sides Pompey have beaten in their fine run.
He said: ‘We lost our grip on the game in the second half and sometimes you have to dig it out – and that’s what we did.
‘They put us under quite a bit of pressure at the end. Obviously Ipswich recently was tough when they played really well in the first half.
‘But Sheffield put us under quite a bit of pressure just by launching it into our area.
‘They gambled, really, throwing five or six people up there. We should have punished them for leaving so many people up, but sometimes you just get penned in.
‘But we dug it out and that was the main thing. They never really created a clear-cut chance.
‘The whole team are working hard for each other, priding ourselves on clean sheets and long may that continue.’
Meanwhile, Hreidarsson was typically understated about his first goal since December 2009.
He added: ‘I just smashed it into the net, it was as easy as that.
‘The ball was going to drop somewhere and it dropped for me.’