Pompey’s winning run finally came to an end, as goals either side of half-time condemned them to defeat against Burton at Fratton Park.
Mike Fondop scrambled home the opener just before the break, while the second half was only a few seconds old when Joe Powell’s fine strike doubled the visitors’ lead.
The Blues were dominant in possession throughout, but were unable to turn that into many meaningful opportunities.
Substitute Charlie Daniels did head a late goal for the hosts, although it proved no more than a consolation.
Danny Cowley made one enforced change from the side that won on the road at Wigan on Easter Monday.
Andy Cannon – who came off the bench to grab the only goal of that game – replaced the injured Michael Jacobs.
Tom Naylor and Marcus Harness both started against their former club, with the latter hitting a hat-trick at the Pirelli Stadium earlier in the season.
Before kick-off there was a two-minute silence in memory of His Royal Highness The Prince Philip, Duke of Edinburgh, who passed away the previous day at the age of 99.
An early effort from Harness was deflected into the side netting, but despite dominating possession, the hosts were unable to create many decent openings before the break.
Likewise, there was not much happening at the other end, although Craig MacGillivray made a regulation stop to deny Fondop.
Andy Cannon did send an excellent cross towards the back post, although both Lee Brown and Ronan Curtis were unable to make a connection.
And the Blues were dealt a blow midway through the half, when Brown limped off injured to be replaced by Daniels.
A Harness delivery was nodded back by Curtis as Pompey tried to force a breakthrough, but Naylor could not guide his shot on target.
Instead it was the Brewers who broke the deadlock against the run of play right on the stroke of half-time.
They needed three attempts to force the ball home, though, after a long throw caused havoc in the box.
The first effort from Hayden Carter was brilliantly saved by MacGillivray, while John Brayford’s follow-up header was hacked from the line by Callum Johnson.
But the ball fell for Fondop and, despite tumbling to the turf, the striker managed to hook it into the net.
Half Time: Pompey 0 Burton 1
There were not even two minutes on the clock when the visitors doubled their advantage in impressive style.
Fondop was fouled 30 yards out and the free-kick was laid off for Powell to smash home an unstoppable shot.
Pompey soon made a double switch, as Sean Raggett and Cannon made way for Rasmus Nicolaisen and George Byers.
They continued to dominate possession and spend plenty of time in the opposition half, but struggled to find a path through the defence to test Ben Garratt.
One patient passing move almost yielded a reward, but after spinning inside the area, a deflected Curtis effort looped into the keeper’s arms.
A last throw of the dice from Cowley saw Harvey White and James Bolton replace Naylor and Johnson.
And Bolton showed great desire to nod the ball down for Curtis inside the box, but the forward could not keep his shot down.
Pompey kept probing, but came close to conceding again late on, with MacGillivray doing well to keep out Lucas Akins’ attempt.
But there was hope for the hosts when Close’s deflected pass, looped up for DANIELS to nod home his first goal for the club.
They continued to apply pressure throughout five minutes of added time, but could not find an equaliser.
Pompey (4-2-3-1): MacGillivray; Johnson (Bolton 73), Whatmough, Raggett (Nicolaisen 53), Brown (Daniels 26); Naylor (c) (White 73), Close; Harness, Cannon (Byers 53), Williams; Curtis
Goals: Daniels 88
Subs not used: Ward, Stanley
Burton (4-2-3-1): Garratt; Brayford (c), Carter, Bostwick, Hamer; Mancienne, Clare (Taylor 83); Powell (Rowe 67), Edwards, Akins; Fondop (Hemmings 67)
Goals: Fondop 45, Powell 47
Subs not used: O’Hara, Earl, Broom, O’Toole
Referee: John Busby