The visitors moved ahead on the quarter-hour mark when Kevin Harper capped an excellent run with a clinical finish into the bottom left-hand corner of Gavin Ward's goal.
Pompey then extended their advantage just past the half-hour. Tim Sherwood tricked his way past two defenders before pulling back a measured cross which Svetoslav Todorov headed accurately home.
But the hosts dragged themselves back into the encounter after some slack defending from Portsmouth's Hayden Foxe.
Brazilian striker Junior pounced on the Australian's error to fire home an angled left-footed drive from eighteen yards.
Colin Lee's men could not find a leveller however, and indeed it was Pompey through Paul Merson who went closest to adding to the scoreline.
Meanwhile, Leicester City are also on the brink of securing a swift return to the Premiership following a 2-0 victory over Grimsby whilst third-place Sheffield United were held away to Crystal Palace.
The Foxes were made to fight all the way by a hard-working Mariners outfit, though second half goals from Trevor Benjamin (pictured) and Callum Davidson broke the visitors' resistance.
City's result was made all the sweeter after in-form Sheffield United were held to a 2-2 at Selhurst Park, though it could have been much worse for the Blades had Steve Kabba not scored a last-gasp equaliser.
Dele Adebola had the home side ahead after 15 minutes when his miskicked effort rolled into the net, before Australian international defender Tony Popovic inadvertently diverted the ball into his own net on 21 minutes.
Noel Whelan soon restored Palace's lead with a lashed effort on 29 minutes, and that goal had looked enough for all three points before Kabba rescued a point.
Ipswich Town's hopes of achieving an unlikely play-off spot were hindered after losing 4-3 to Nottingham Forest in a thrilling affair at Portman Road.
It all started so well for the home side when Tommy Miller's brace put Town 2-0 up, though three goals in just seven minutes from Forest stunned the home faithful.
Substitute John Thompson pulled a goal back on 26 minutes before Marlon Harewood equalised moments later with a fortuitous effort whilst an own goal from Richard Naylor put the visitors ahead.
Marcus Bent then scored the sixth goal of the game when he equalised on the hour mark, though there was a sting in the tail when Harewood headed in his 21st of the season to earn Forest all the points.
Wolverhampton's hopes of cementing their play-off spot were hindered after being held to a goalless draw at home to Rotherham despite playing the majority of the match with only 10 men.
Nathan Blake was the villain for Wolves after being dismissed 15 minutes in, though Dave Jones's men could have nicked the points had Colin Cameron converted a second-half spot-kick.
Watford's on-loan striker Michael Chopra, who could still appear for The Hornets in their FA Cup semi-final, was the hero as he netted four goals in their 7-4 win over Burnley at Turfmoor.
The Clarets have already been involved in one goal-fest this season following their 6-5 loss to Grimsby at Blundell Park, and were on the wrong end of yet another at the hands of The Hornets.
Wayne Brown put the visitors ahead after 13 minutes, though Gareth Taylor pulled the first of his three goals back just moments later.
Micah Hyde restored Watford's advantage seconds later, before efforts from Neil Cox and Chopra sent the Vicarage Road side 4-1 up.
Steve Davis and Taylor's second pulled it back to within one, though all hope looked lost for Stan Ternent's men when Chopra made it 5-3.
There was still time though for Taylor to net his hat-trick and cap a thrilling first-half, however another brace from Newcastle youngster Chopra after the interval sealed a remarkable away win for The Hornets.
Derby pulled away from the drop zone with a crucial 2-1 home victory over high-flying Norwich City at Pride Park.
It was the worst start imaginable for temporary boss George Burley after former Tottenham striker Paul McVeigh scored a superb individual effort after 10 minutes.
Burley was not to be denied on his debut though and nephew Craig Burley levelled matters with a right-footed effort on 24 minutes.
The Rams' winner proved a real howler for Canaries' keeper Robert Green who allowed Darren Kenton's back-pass run under his foot and into the empty just before the hour mark.
Sheffield Wednesday kept their faint hopes of avoiding the drop alive with a vital 4-2 home win over Wimbledon, despite squandering a two-goal lead.
Michael Reddy and Lloyd Owusu put The Owls in control, though two goals in just two minutes from David Connolly and Patrick Agyemang brought The Dons back from the dead.
With home fans' nerves jangling Owusu netted his second of the game, allowing Chris Turner a big sigh of relief, before on loan Lee Bradbury made sure of the points with a late fourth.
Elsewhere, Pawel Abbott earned Preston a share of the spoils against Coventry at Deepdale after netting a late equaliser.
Richard Cresswell gave Dale a first-half lead, though efforts from Craig Pead and David Pipe put The Sky Blues in command.
With Gary McAllister counting down the seconds on his watch, Abbott, who only recently rejoined the club from a loan spell, nipped in to steal a draw.
Stoke's 0-0 draw at home to Gillingham has done them few favours in their bid for survival, whilst an injury-time goal from Neil Harries earned Millwall a 1-0 victory over Bradford at Valley Parade.
Click here Division One summaries:
Bradford 0-1 Millwall
Burnley 4-7 Watford
Crystal Palace 2-2 Sheff Utd
Derby 2-1 Norwich
Ipswich 3-4 Nottm Forest
Leicester 2-1 Grimsby
Preston 2-2 Coventry
Sheff Wed 4-2 Wimbledon
Stoke 0-0 Gillingham
Wolverhampton 0-0 Rotherham
Click here for an updated league table.
