Eddie Howe's return to the south coast proved to be a memorable one as he secured his first win as Burnley manager to breathe new life into the Clarets' play-off campaign.
Howe's time as a Portsmouth player was ruined by injury but back at Fratton Park he finally made his mark by cajoling Burnley to only their second away win of the season and third in over 18 months.
Happy return for Eddie Howe
With that kind of record the former Bournemouth boss was dealt a tough hand with his first three league games in charge of the Clarets sending him out on the road.
A return of four points from his first two games therefore makes it a highly satisfactory start as first-half goals from Jay Rodriguez and Dean Marney continued Portsmouth's miserable run under former Burnley manager Steve Cotterill.
The goals came either side of a quick riposte from John Utaka in dramatic six-minute spell, with Marney's spectacular strike a worthy winner as the Clarets then resolutely hung on to claim all three points and a first victory over Pompey in 12 attempts and 29 years to climb back towards the top six.
Burnley's starting line-up included three players signed by Cotterill during his Turf Moor reign, as well as Steven Thompson as Howe gave the striker, awaiting an appointment with a specialist to assess an on-going groin problem, an opportunity to impress.
Thompson took it with a battling performance up front, while on the other side of the fence, Pompey included ex-Clarets' loanee David Nugent and it was Nugent who almost created the opening goal after just seven minutes.
His crisply struck shot bounced awkwardly for goalkeeper Lee Grant, whose parry fell for Liam Lawrence to strike a hurried effort over the bar.
Match-winner Dean Marney moves in to tackles Kanu
Burnley weren't slow to carry the attack to the home side but the cutting edge that had deserted them in recent games was absent early on as too much broke down around the penalty area.
Their first real opening took 20 minutes to arrive before Clarke Carlisle, who shook off a knee injury to retain the captaincy, diverted a Jack Cork shot goalwards and appealed for penalty when his effort was blocked by a pile of bodies in front of goal.
The Clarets had been guilty of failing to deliver the killer ball from some promising positions but with half an hour gone that all changed when Danny Fox joined the attack to devastating effect as Burnley went ahead with the first goal of the Howe era.
Despite stumbling as he broke over half-way, the left-back steadied himself and whipped in the perfect near-post cross for Rodriguez to calmly side-foot his sixth goal of the season.
With Pompey not having won on their own turf since the end of October it was the last thing they needed but Burnley were unable to hold onto their lead for more than two minutes as the hosts hit back almost immediately.
Flying high: Steven Thompson
Veteran striker Kanu was the creator with a typically inventive through-ball for Utaka, who lifted the ball over Grant for his second goal in four days.
The momentum might have swung Pompey's way but instead it was the Clarets who grabbed the lead again with a third goal in the space of six frantic minutes to lead 2-1 at half-time.
Thompson almost marked his return by getting on the scoresheet after pouncing on a mistake by Greg Halford. But although his effort was well saved by Jamie Ashdown, Pompey failed to clear and Marney punished them superbly with an acrobatic overhead kick into the bottom corner of the net from 15 yards out.
Portsmouth would have hoped to put the Clarets' recently re-discovered defensive resolve to the test after the break but Cotterill's men were kept fairly comfortably at arm's length, despite an increasing amount of possession going their way.
Grant took the precaution of tipping a looping Kanu header over the bar but mid-way through the second half it was the Clarets who went closest to increasing their advantage.
Wade Elliott battles for the cause
Ibrahima Sonko headed a Wade Elliott cross onto the top of his own crossbar and although the corner was half cleared, Marney fired the ball back in for Rodriguez to glance in a header which had Ashdown flying across his goal to save.
The Clarets would have loved the cushion of a two-goal lead and were almost pegged back with 18 minutes to go.
Dangerman Nugent got in behind the visitors' defence but rather than shoot he elected to try and pick out Utaka and Tyrone Mears came to the Clarets' rescue with a vital interception.
Utaka then burst through and poked a shot just wide of the far post as Pompey cranked up the pressure.
The winning feeling
But the Clarets bravely soaked up everything thrown at them to keep Portsmouth at bay and and get the Howe era up and running in with a potentially pivotal result.
Burnley: Grant, Fox, Carlisle, Duff, Mears, Cork, Elliott, Marney, Rodriguez, Thompson (Iwelumo 87), Eagles (Alexander 90). Subs: Edgar, Bikey, Wallace, Easton, Jensen.
Booked: Cork 39, Duff 88
Pompey:Ashdown, Halford, De Laet, Lawrence, Mullins, Nugent, Hogg (Hreidarsson 89), Utaka, Ward, Sonko, Kanu (Dickinson 64). Subs: Ciftci, Rocha, Kilbey, Flahavan.
Referee: Stuart Atwell.