This time there was no glorious comeback, no last-gasp drama.
Harry Kane did the damage in the 37th minute, a clever finish, albeit against the run of play.
It allowed plenty of time for Michael Appleton’s men to rally as they did at St Mary’s at the weekend.
Except the fightback did not emerge.
That Kane goal didn’t merely deliver a body blow to Pompey’s hopes of a positive result on the night, it also effectively sucked the life out of their survival bid.
The simple truth now is the Blues could be relegated at Doncaster on Saturday.
Of course, there are bigger, far more important battles ahead, such as the club remaining in existence.
In the meantime, in terms of what division the Blues could be featuring in next season, that will become a little clearer at the Keepmoat Stadium.
That stark scenario was thrown up following last night’s 1-0 defeat at Fratton Park.
Pompey started brightly enough, clearly still buoyant following that Southampton draw only three days earlier.
Maik Taylor produced a smart double save from both Chris Maguire and then Luke Varney as early as the fifth minute.
As the half wore on, the hosts were comfortable. They were in control, without really putting too much pressure on the Millwall keeper.
Then came that decisive Kane moment.
As Pompey tried to find an equaliser, Jason Pearce saw his header pushed on to the bar by Taylor in the 86th minute, while David Norris had appeals for a penalty turned down moments earlier.
Kelvin Etuhu then saw a vicious left-foot shot brilliantly turned behind in stoppage-time.
That was it for Pompey, though, as their night spiralled into disappointment following such joy across the south coast on their previous outing.
It means, come Saturday, if Bristol City better the Blues’ result at Doncaster, Pompey will be condemned to League One.
Unsurprisingly, Appleton retained the same side which pulled off the 2-2 draw against Southampton at the weekend.
That meant Greg Halford keeping his spot in the centre of midfield, with Joel Ward continuing at right-back.
The only change to that St Mary’s squad was Benjani named instead of Dave Kitson on the bench.
Elsewhere, Tal Ben Haim and Aaron Mokoena were still sidelined by injuries, while there was once more no place for Kanu, who has been linked with a summer move to Qatar.
When the game started, it was Pompey who were quicker out of the blocks, clearly still buoyed by that Southampton result.
As early as the fifth minute, Maguire surged through the heart of the Millwall defence and fired in a shot which Taylor parried.
Varney swooped to steer a follow-up goalwards but Taylor reacted brilliantly to also keep out that effort.
Moments later, Scott Allan dribbled around several Lions players to break into the box, but Paul Robinson produced a superb block tackle to dispossess him.
The hosts were in control, producing some crisp, slick football and roared on by the excellent Fratton faithful.
In the 15th minute, Halford won the ball 35 yards out and crashed in a drive which was comfortably taken by Taylor.
Despite being on top, Pompey were struggling to carve out many clear-cut opportunities, although on 23 minutes, Halford sent a header from a corner just over the bar.
Joel Ward then whipped in a cross from the right which James Henry almost ended up heading in at the far post, instead the ball flashed narrowly wide for a corner.
Millwall did have their moments, though, Scott Barron firing a volley which kept low and forced a sprawling save from Ashdown.
Norris then threaded a pass through to Maguire to free him inside the box, yet his curling right-foot effort was well saved by Taylor.
But it was Millwall who took the lead in the 37th minute against the run of play.
Kane produced a clever turn inside the area to wrong foot marker Ricardo Rocha, buying him enough space to place a shot into the bottom right-hand corner.
It was a sublime finish from the teenage striker to stun the home faithful.
Pompey were wobbling and Josh Wright crashed a 30-yard shot just over the bar as Millwall seized control.
On the stroke of half-time, Marko Futacs came on to replace the limping Rocha, with Halford dropped back into the centre of defence.
Appleton’s men started slowly after the break, although in the 52nd minute Futacs did swivel and fire a rocket narrowly over the bar.
Kane went close with a far-post header which flashed across goal after meeting Wright’s deep cross from the left-hand side.
In the 68th minute, Futacs controlled Ward’s header on his chest before letting fly with this left foot which Taylor gathered at the second attempt.
There were Pompey appeals for a penalty six minutes from time when Norris went down under a challenge from Smith inside the box.
However, referee Mark Halsey remained unmoved, much to the home crowd’s fury.
The fourth official indicated an additional three minutes of time added on and Etuhu drew a tremendous save from keeper Taylor.
But that was it, the final whistle bringing a close to the match. And, unless there are a remarkable turn of events, Pompey’s time in the Championship.