The unbeaten away record has stretched into an improbable fifth month for Kenny Jackett’s side.
And it has earned Pompey rare recent FA Cup progress in a match in which they were fortunate to claim victory.
The Blues looked tired and lacked second-half sparkle in a Spotland visit which marked the start of 10 matches in 35 days.
Indeed, as the second-round affair progressed, Rochdale began to dominate Jackett’s leggy troops, applying rising pressure.
Then, on 90 minutes, substitute Andre Green’s deflected shot kindly found the net to break the hearts of a gallant Dale.
While Pompey had been comfortably the best side in the opening 45 minutes, they were a shadow of their usual selves after the break as they began to wilt.
It allowed Keith Hill’s men to seize the initiative, yet they were unable to find a way through as the tie headed towards a replay to add to Pompey’s gruelling schedule.
Granted, Ronan Curtis struck the bar in the the first half, but left-back Matt Done clattered the woodwork in the second as the rejuvenated hosts searched for a winner.
As it was, Green, on as a 76th-minute substitute for Jamal Lowe, provided the decisive moment to send the Blues into the next round.
It represents only the second time in seven seasons that Pompey have reached the third round, the other occasion when eliminated by Bournemouth at the fourth-round stage in 2015-16. Jackett’s troops didn’t deserve to overturn their hosts without a replay in their third Spotland meeting in the past seven-and-a-half months.
It was unconvincing, below-par and laboured, yet this is a team blessed with heart and guts, excellent characteristics once more demonstrated in this match.
The outcome is 13 games unbeaten away from home in all competitions since the start of the campaign.
And, rather fortunately, progress in the FA Cup to set up a tantalising wait to see who lies in wait when the Premier League teams enter proceedings.
With Tom Naylor absent from action following a knock, Jackett made an enforced change to the side which won against Walsall in the week.
Ben Close came in as a holding midfielder to partner Ben Thompson as the only alteration, the Blues again naming a strong side in the competition.
The in-form attacking quartet of Oli Hawkins, Gareth Evans, Jamal Lowe and Ronan Curtis – who had each scored seven goals heading into the Spotland encounter – again started.
That meant Brett Pitman once more on a bench now missing David Wheeler, who suffered a hamstring concern against the Saddlers.
However, Danny Rose was called into the matchday 18 for only the seventh time of a frustrating personal campaign for the popular midfielder.
In addition, there was the inclusion of Anton Walkes among the substitutes, having answered his court case for driving while disqualified and driving without insurance.
With Joe Mason and Dion Donohue still injured, the only other notable absentee was Louis Dennis.
The incessant rain had subsided by the time the match got under way, yet there were still dark skies over Greater Manchester.
In the opening exchanges, Evans was injured following a foul by Stephen Dooley, a challenge which angered the Blues players, who surrounded the referee.
However, the skipper was able to continue, with Dooley receiving a talking-to from the match official.
On seven minutes, Nathan Thompson delivered a cross from the right which was met by Oli Hawkins, yet defender Harrison McGahey managed a partial block and Dale’s keeper gathered comfortably.
The hosts had a golden opportunity to break the deadlock on 11 minutes following a booming goal-kick from Josh Lillis.
The ball found its way to Jordan Williams inside the box, who controlled on his chest before dragging the ball wide when he should have done far better.
At the other end, Ben Thompson wriggled into the opposition penalty before firing a right-footed shot over the bar from the angle.
Then, on 24 minutes Close calmly launched a counter attack by feeding Evans and his left-foot shot on the charge flashed wide.
Pompey continued to look the most likely to break the deadlock and Evans crashed a volley which just cleared the bar following Oli Hawkins’ flick.
The match was proving a largely subdued affair during the first half, although Craig MacGillivray’s kick out of his hands did find Curtis, whose right-foot shot was straight at the keeper.
On 41 minutes, Hawkins and Evans combined to tee up Lowe, whose left-footed shot ballooned over the stand behind the goal and out of the ground, albeit having taken a bobble.
Moments later, Ian Henderson had Rochdale’s best chance with a sweetly-struck angled shot from the right which flashed agonisingly past the far post.
Pompey hit the bar, Curtis surging forward on 43 minutes and smashing a right-footed against the woodwork with the keeper beaten.
As the visitors’ late first-half flurry continued, Lowe earned a yellow card for clearly diving inside the penalty area.
The game was goalless at the break and, shortly after the restart, Dooley won a free-kick 20 yards out after Close’s foul.
That was taken by Done, but struck the wall and was cleared by the visitors.
Dooley didn’t last much longer and was replaced by Andrew Cannon on 55 minutes for the game’s first substitution.
Pompey were failing to match their form before the break and were indebted to MacGillivray’s save with his feet to deny Calvin Andrew on 63 minutes.
Then Done struck the corner of the bar and post on 69 minutes having broken forward from his left-back role.
Pompey made their first substitution on 72 minutes, with Pitman replacing Evans, coinciding with Jack Whatmough heading wide at the far post following Brown’s free-kick.
Still the teams couldn’t be separated and when Lillis couldn’t hold Curtis’ stinging shot from outside the box, the keeper was able to sweep up without too much fuss.
Then, on 90 minutes, Ryan Delaney cleared out substitute Green on the edge of the area, collecting a booking in the process.
From the free-kick, Brown rolled the ball to the left for Green to fire in a shot took a wicked deflection and looped into the far corner.
The fourth official indicated an additional four minutes of time added on and, in the dying seconds, MacGillivray flung himself to his left to keep out Henderson’s attempt to ensure victory was Pompey’s.