John Mousinho’s men surrendered position for all three of the League One side’s goals, while they also conceded in the opening 90 seconds of each half.
Thomas Waddingham came off the bench to reduce the deficit in stoppage time with a header from John Swift’s cross, but it couldn’t mask a poor showing.
And here are our Pompey player ratings...
5. Madiodio Dia - 6
(Replaced by Regan Poole on 61 mins) Good physical presence defensively and never lets a striker settle. Lacked accuracy with his attempts at crossfield passing. | Simon Roe/ProSportsImages
6. Jordan Williams - 6
(Replaced by Arvin Appiah on 46 mins) - Again asked to play left-back and Wycombe’s early goal came from that flank. Struggled to get an understanding with Blair in front of him. | Simon Roe/ProSportsImages
7. Rocco Shein - 6
(Replaced by John Swift on 46 mins) Handed his first Blues start after his Bristol Rovers substitute outing. A couple of neat touches in the centre of midfield, while producing several accurate passes to the wings. Steady enough. | Dan Minto/ProSportsImages
8. Odin Bailey - 5
(Replaced by Ebou Adams on 78 mins) Badly caught in possession in the build up to the third goal as he attempted to wriggle past two players. Tried to keep things ticking over, but struggled to inspire the Blues. | Simon Roe/ProSportsImages