Colby Bishop found the target as Pompey continued their fine start to the season by beating Exeter at Fratton Park.
Both sides approached the televised contest looking to protect an unbeaten record and it was the hosts who seemed more likely to score.
And the goal arrived in emphatic fashion from last term’s leading marksman Bishop midway through the second half.
But it took a fantastic save from Will Norris at the death to ensure the Grecians would head back to Devon empty-handed.
John Mousinho made two changes from the side that won so convincingly at Leyton Orient at the weekend.
Alex Robertson was handed a full debut and Anthony Scully returned to the starting line-up, as Christian Saydee and Abu Kamara dropped to the bench.
The first half was certainly a lively affair, even if it took until the latter part for the clear-cut openings to arrive.
Pompey were looking to patiently build possession and wait for an opening that they could try to exploit.
Scully and Gavin Whyte were trying to threaten out wide, while Bishop tested the handling of Viljami Sinisalo.
But their first decent chance arrived on 29 minutes, when Robertson shimmied past a challenge and hit a fierce shot that was pushed clear by the Finnish stopper.
And Sinisalo had to be at his best again moments later, parrying away Connor Ogilvie’s drilled effort from the edge of the box before Will Aimson hacked the loose ball clear.
Norris was a virtual spectator at the other end, although he did have a simple shot to save following Dion Rankine’s dangerous break.
But it was the Blues looking more likely to break the deadlock as the interval approached, as Bishop collected Joe Rafferty’s cross and forced Sinisalo into action.
Rafferty then found himself on the left and his low centre somehow evaded everyone and flashed just past the post.
And deep into stoppage-time, Manchester City loanee Robertson was picked out by Scully and fired a inches wide.
Half Time: Pompey 0 Exeter 0
Pompey were first to threaten after the break when Robertson brought the ball down superbly and found Scully, but Rankine was able to get it clear.
Norris dealt with Pierce Sweeney’s awkward free-kick in an unorthodox manner at the other end, but it proved effective.
The hosts were trying their best to plot a way through the Grecians back-line and when Rafferty did find Whyte in the area, he screwed his shot wide.
And the impressive Robertson then fired narrowly over from 25 yards after Bishop had been brought down.
Exeter still fancied the win for themselves, however, and Zak Jules nodded a Reece Cole delivery into the arms of Norris.
It was fast turning into an open contest that saw the sides taking it in turn to launch threatening attacks.
Mousinho freshened up the wide areas on 68 minutes, with Scully and Whyte replaced by Kamara and Jack Sparkes, who had arrived from the Grecians over the summer.
And the latter had a role in the goal that broke the deadlock moments later after Sinisalo’s clearance only flew as far as Marlon Pack.
He nodded the ball to Sparkes, who in turn played it to BISHOP and the striker spun Alex Hartridge with ease before finding the net with a thumping finish.
Exeter tried to hit back, but the ball flew over the bar when a corner took a deflection and bounced off skipper Aimson.
Robertson then received a standing ovation as he made his way off the pitch, with Saydee on to replace him.
There was a late delay when one of the referee’s assistants picked up an injury and had to be replaced by the fourth official for the final few minutes.
It looked like the visitors would level when the action restarted, only for Norris to somehow keep out Sweeney’s header at point-blank range.
The display of a minimum nine added minutes drew groans from the Fratton faithful, but Pompey saw it out to claim a maiden home win of the season.
Pompey (4-2-3-1): Norris; Rafferty, Poole, Shaughnessy, Ogilvie; Morrell (Raggett 90+2), Pack (c); Whyte (Sparkes 68), Robertson (Saydee 81), Scully (Kamara 68); Bishop
Goals: Bishop 70
Booked: Poole, Sparkes, Robertson, Ogilvie, Shaughnessy
Subs not used: Schofield, Swanson, Yengi
Exeter (3-4-3): Sinisalo; Sweeney, Aimson (c), Hartridge (Taylor 88); Rankine, Trevitt, Carroll (Cox 78), Jules (Harper 78); Scott (Cole 59), Aitchison, Mitchell (Nombe 59)
Subs not used: Woods, Borges
Referee: Tom Reeves
Attendance: 17,592 (530 away)