Pompey ran riot at Colchester to strengthen their position inside League Two’s top three.
It was a display of attacking supremacy from the Blues, who arguably deserved to win by more than the four-goal margin.
Eoin Doyle got the ball rolling during a first half that saw the visitors grow stronger as it progressed.
And they moved comfortably through the gears after the interval, as Kyle Bennett, Danny Rose and Michael Doyle all got in on the act.
Paul Cook stuck with the same side that comfortably beat Crawley earlier in the week.
But it was the hosts who made the brighter start and Brennan Dickenson did well down to the left, only to let himself down with the ball into the box.
Pompey soon began to settle and threaten going forward themselves, though, with some neat attacking play.
Eoin Doyle could not quite get on the end of an excellent Carl Baker cross, while a snap-shot from Kal Naismith was safely held by Colchester keeper Sam Walker.
Then when a cross was only partially dealt with by the United defence, Enda Stevens followed up with a volley that Walker was able to collect.
But the Blues did break the deadlock on 22 minutes, with Naismith sending the ball back into the box after his corner had been blocked and Eoin DOYLE heading home from close range.
He was not too far away from adding another soon after, but could not quite get on the end of Bennett’s near-post delivery.
And the on-loan Irishman then capitalised on some hesitancy by George Elokobi to deal with Stevens’ floated pass, only to send his shot over the bar.
Meanwhile, there was little to trouble the visitors at the other end of the pitch, as they comfortably held on to their lead at the break.
Colchester United 0
Colchester replaced Sammie Szmodics with Tarique Fosu at the interval in an attempt to improve their fortunes.
But instead Pompey found themselves further ahead just seconds after the restart – much to the delight of their large travelling army.
And it was BENNETT who doubled his tally for the week when, following good work down the right, Naismith selflessly squared for the winger to tuck home.
United came close to reducing their deficit moments later, but a stretching Chris Porter could not quite reach Dickenson’s cross.
But the Blues were still looking to get forward themselves and when Colchester switched off from a throw, Bennett picked the ball up and neatly side-stepped his man before blazing the shot wide.
Stevens then collected Naismith’s shot free-kick and beat a defender, only to see his arrowed drive deflected just past the post.
United were looking all at sea and it came as no surprise when Pompey extended their advantage further just past the hour mark.
Eoin Doyle did well to slide the ball through to ROSE, who saw his first shot blocked by Walker before neatly dinking home at the second attempt.
The keeper was almost caught out by Naismith moments later, but quickly back-pedalled to claw the ball clear.
Colchester had not created much at the other end and when they finally did get forward, it led to Pompey’s fourth goal.
The visitors broke quickly up the pitch from a corner, with Michael DOYLE surging forward to tuck away his first of the season after Naismith’s initial effort had been saved.
That was Naismith’s last bit of action, as he was immediately replaced by Noel Hunt, with Gary Roberts and Conor Chaplin joining him on the pitch soon after.
And there were no nerves in the closing stages as Pompey comfortably saw the game out to complete an enjoyable afternoon in Essex.
Colchester (4-2-3-1): Walker; Wright (Vincent-Young 66), James, Elokobi, Briggs; Garvan (Bonne 68), Lapslie; Murray, Szmodics (Fosu 46), Dickenson; Porter (c)
Subs not used: Barnes, Wynter, Kinsella, Pyke
Pompey (4-2-3-1): Forde; Evans, Burgess, Clarke, Stevens; Rose, M.Doyle (c); Baker, Naismith (Hunt 74), Bennett (Roberts 77); E.Doyle (Chaplin 84)
Goals: E.Doyle 22, Bennett 46, Rose 61, M.Doyle 73
Subs not used: O’Brien, T.Davies, Linganzi, Lowe
Referee: Darren England
Attendance: 6,504 (2,244 Pompey fans)