Pompey suffered their first defeat of pre-season, as they narrowly went down at League Two outfit AFC Wimbledon.
The only goal arrived midway through the first half, when the ball deflected into the net off the unfortunate Ben Stevenson.
There was plenty of pressure applied by the Blues after the interval, but they could not find an equaliser at Plough Lane.
Colby Bishop took part in the warm-up, but was not named in the squad, while Sean Raggett missed out with a slight back spasm.
Pompey were backed by more than 1,200 noisy travelling fans under bright evening sunshine in the capital.
And it was the visitors who settled quickest, dominating the early stages, without being able to test Nik Tzanev between the sticks.
The closest they came to breaking the deadlock came courtesy of a Gavin Whyte effort that cleared the crossbar.
Armani Little, meanwhile, seemed to be confused about what sport he was playing and got penalised for a rugby tackle on Christian Saydee.
It was his side who broke the deadlock on 27 minutes, though, following good work from Ali Al-Hamadi on the right.
He sent a low delivery into the mixer and the ball ricocheted off an unfortunate Stevenson and into the net.
Pompey struggled to recover from that setback and looked disjointed for the remainder of the first half.
They might have been punished further, but both Al-Hamadi and Aaron Sasu sent attempts straight into the arms of Will Norris.
The Blues finally threatened just before the interval, with Anthony Scully’s corner only partially cleared and Tzanev eventually claiming the loose ball.
Half Time: AFC Wimbledon 1 Pompey 0
Zak Swanson and Josh Oluwayemi both came on for the start of the second half, with Joe Rafferty and Norris making way.
And it was Swanson who tried his luck shortly after the restart, although the angle was always against the winger at the back post.
The Dons soon had an opening at the other end, with Oluwayemi quickly off his line to deny Aaron Sasu.
Pompey’s best chance came just before the hour mark, as Tom Lowery collected Scully’s pass and fired in a low shot that was well saved low to Tzanev’s right.
The keeper also dealt with another Scully delivery from the left before Regan Poole made way for fellow summer signing Conor Shaughnessy.
And the visitors were suddenly posing a real threat, with Tzanev coming to the rescue again to deny Scully following good work down the middle from Stevenson and Saydee.
Kusini Yengi and Paddy Lane added some fresh attacking legs for the final quarter, with Scully and Whyte replaced.
It was Lowery who was next to test Tzanev, though, with a deft flick to end a passage of fine passing play from the visitors.
Pompey were certainly committing bodies forward in search of an equaliser and Lane twice saw efforts blocked, appealing that the second came off the arm of Lee Brown.
But AFC Wimbledon almost snatched a second goal late on, with Shaughnessy well placed on the line to deny Josh Davison.
AFC Wimbledon (4-4-2): Tzanev; Belahouan (Lewis 50), Sutcliffe (Ogundere 75), Pearce (c) (Johnson 85), Brown; Sasu (Neufville 85), Bendle (Reeves 75), Little (Ball 46), McLean (Tilley 75); Pell (Bugiel 85), Al-Hamadi (Davison 63)
Goals: Stevenson 27 (og)
Subs not used: Bass, Currie, Williams, Lock
Pompey (4-2-3-1): Norris (Oluwayemi 46); Rafferty (c) (Swanson 46), Poole (Shaughnessy 60), Towler, Ogilvie (Sparkes 76); Lowery (Morrell 76), Stevenson; Whyte (Lane 69), Kamara, Scully (Yengi 69); Saydee (Devlin 76)
Sub not used: Pack
Referee: Craig Hicks
Attendance: 3,047 (1,215 Pompey fans)