Two second-half goals from Andronicos Georgiou saw Pompey fall to a 3-2 pre-season defeat at Stevenage.
The Stevenage sub gave his side the win after Gareth Evans' first-half finish was cancelled out by Ben Kennedy.
Conor Chaplin, who finds his future subject of continued speculation, tucked away a late consolation.
There were Pompey positives, particularly in wide areas with Lee Brown, Ronan Curtis and Jamal Lowe in the first half, for Kenny Jackett's side.
But they were opened up too many times after the interval as the League Two outfit broke on them in numbers.
Adam May went close to opening the scoring in the 10th minute with a 20 yarder which keeper Paul Farman did well to push away to left.
Tom Naylor produced a lovely through ball to Curtis in the 17th minute, but Farman was equal to the Irishman's finish.
The lead came in the 20th minute when Evans found space in the box and curled in a finish.
Ben Kennedy was inches away from levelling with a spectacular curler from the apex of the box in the 29th minute, but his effort was just wide.
There was no Kennedy let-off seconds later, though, when he got away from Matt Clarke and advanced before confidently finishing.
There was a flurry of Stevenage triallists introduced at the break, but Pompey first threatened in the 51st minute after the ball was headed wide by Pitman after Curtis' trickery and cross.
But the home side took the lead in the 57th minute when Andronicos Georgiou cracked a 25 yarder which went in with the aid of significant deflection.
Lowe responded by linking up with Thompson before smashing a shot off target from the byline
Pompey made four changes in the 62nd minute with Danny Rose, Chrstian Burgess, Oli Hawkins and Conor Chaplin replacing Adam May, Jack Whatmough, Gareth Evans and Brett Pitman.
Hawkins couldn't get his header on target from another decent Brown cross in the 69th minute.
But Georgiou helped himself to a second with 20 minutes remaining as he produced a fierce finish from Sonupe's cross.
Curtis won the ball in the box and cracked a shot off the post in the 80th minute and then hit a 30 yarder not too far over three minutes later.
Brandon Haunstrup replaced Tom Naylor who hobbled off in 84th minute.
Nathan Thompson then dragged his shot wide after bursting into the box.
Sub Chaplin delivered a typical piece of predatory finishing in the 89th minute to get Pompey a consolation.