So the run is over, inflicted by a mistake and a counter-attack.
Exeter defended heroically, they stood their ground, and departed Fratton Park with a hard-earned victory.
Pompey had been seeking to extend their league start to 10 matches undefeated – surpassing Harry Redknapp’s promotion-winning side of 2002-03.
But despite bossing last night’s fixture, they came undone against a disciplined and highly-organised Grecians team who netted in each half.
Played under new floodlights situated on top of the Fratton end, Milton end and North stand, the supporters had turned up anticipating more winning progress from the league leaders.
Instead, they departed with the Blues dropping to third in the table and nursing a maiden league defeat of what has developed into an encouraging campaign.
When the visitors took the lead through a superb finish from David Wheeler in the 20th minute, Pompey should have already been ahead following a string of chances.
At the time they had enjoyed 81-per-cent possession – then Danny Hollands was caught on the ball 30 yards from goal and Wheeler did the rest.
After the break the hosts continued to push, but a counter-attack sparked from what Gareth Evans believed had been a foul on him in the 56th minute sealed the victory.
There were also appeals for offside against Lee Holmes, however Arron Davies’ header counted to create an unassailable 2-0 lead.
Danny Butterfield cleared off the line from Jayden Stockley, and substitute Matt Tubbs should have netted with a header as Paul Cook’s men poured forward.
Yet Exeter stood firm, maintaining their shape under some fierce Blues pressure to pull up the drawbridge and keep them at bay.
Substitute Gary Roberts did provide late hope deep into stoppage-time with a deflected shot from long range to reduce the arrears.
However, seconds later the curtain was brought down on a 2-1 result for the gutsy Grecians sporting a first Fratton Park win for 93 years.
Now Pompey must start their run all over again on Saturday as Yeovil travel to the south coast.
Cook kept an unchanged side for the game, despite the availability of Michael Doyle following suspension.
Surprisingly, the Blues’ captain was restricted to a place on the bench, with Adam Barton and Hollands continuing their holding-midfield partnership.
There was a return to the squad for Nigel Atangana after a back injury.
He also joined Doyle on the seven-man bench for last night’s fixture.
There was no starting XI recall either for Roberts, irrespective of his impressive Memorial Ground cameo which turned the match in Pompey’s favour.
His ankle knock is being monitored by Cook and his staff, yet the midfielder found himself among the substitutes for the second fixture running.
Once more Adam McGurk (ankle), Paul Jones (knee), Michael Poke (shoulder), Brian Murphy (groin) and Jack Whatmough (knee) remained on the sidelines and out of contention.
Pompey started brightly, with Evans twice thwarted from breaking the deadlock through some rugged Exeter defending.
Conor Chaplin pulled the ball back from the left and Evans’ first shot was blocked by keeper Bobby Olejnik, with his follow-up towards a crowded goal line then crashing against the flying body of Jordan Moore-Taylor.
Ben Davies then retrieved the loose ball and delivered a deep cross from the right which was met by Stockley’s header.
However, it flashed wide.
On eight minutes the Blues won a free-kick 25 yards from goal following a handball by Troy Brown, with Kyle Bennett taking the dead ball and firing it over the bar.
Exeter won their first corner on 11 minutes but the hosts soon launched a dangerous counter-attack through Enda Stevens’ ball over the top – but Evans’ cross drifted out of play.
The Fratton faithful were then on their feet in the 18th minute, after a delicious move started by Stevens deep in his own half.
It ended in Stockley delivering a first-time cross from the right and Chaplin sliding in at the far post, with the visitors scrambling the ball out for a corner.
Yet completely against the run of play Exeter took the lead in the 20th minute.
Hollands was dispossessed by Wheeler 35 yards from goal and the striker surged forward and unleashed an angled right-foot effort which found the far corner of the net.
Pompey responded with Bennett pulling a left-wing corner back to Stevens, who took a touch before rifling a shot from distance over the bar.
Buoyed by their advantage, Exeter were not far off grabbing a second on 26 minutes, when a left-wing corner was partially cleared and Davies rifled a first-time shot just wide.
A delightful move by the hosts on 41 minutes saw Chaplin backheel the ball into the path of Bennett, whose right-foot shot from outside the area was comfortably plucked out of the air by Olejnik.
Despite being in the lead at the interval, the Grecians made a change, with David Noble coming off for Butterfield.
The hosts had the first opportunity of the second half, with Bennett cutting across from the left-hand side and firing a shot from outside the box which was easily gathered.
Then Stevens crossed a ball into the box which was headed into the path of Evans by Stockley, yet the midfielder agonisingly couldn’t reach it and instead took out Brown.
Cook brought on Tubbs in the 55th minute in place of Chaplin, yet within a minute Pompey found themselves further behind.
Initially, home keeper Aaron McCarey saved well from Christian Ribeiro, with Stockley hacking the ball clear.
Then, when Evans went down under a challenge up field, the visitors broke through Holmes down the left, with some of the Fratton faithful appealing for an offside flag.
Regardless, his cross was pushed out by the keeper and there was Davies to steer the ball into an empty net with his head.
On 65 minutes, Bennett’s right-wing corner was met with a powerful Stockley header and Butterfield hacked the ball off the line when positioned on the left-hand post.
That prompted the introduction of Roberts in place of Evans into what was now a 4-4-2 formation, with Tubbs and Stockley leading the line.
Pompey were pouring forward and, when a cross came from the right, Stevens produced a header on the bounce which was clawed away by Olejnik as it threatened to loop over him.
Tubbs also went close, before Roberts’ shot took a deflection and reduced the deficit to 2-1 deep into stoppage-time.
However, the Grecians hung on for victory to mark the end of that impressive Blues start to the league campaign.