Pompey reserves were made to pay for failing to take their chances as they crumbled to a 4-1 loss to their AFC Wimbledon counterparts.
A hat-trick from David Fitzpatrick and a goal from Tom Beere left substitute Calvin Davies’ strike as nothing more than a consolation with the Dons deserved winners at Ryman league division one venue Merstham’s home ground
Wes Fogden got through another 70 minutes as he continued his recovery from a lengthy injury lay-off and showed glimpses of his old sharpness returning.
But Wimbledon started the brighter of the two sides and were first to threaten after good work from Fitzpatrick allowed Dan Agyei a shooting opportunity, but the striker could only steer his effort wide of the far post when well placed.
The same man went close again inside 10 minutes when he controlled well on his chest and produced a sharp turn, but his volley whistled wide of Michael Poke’s upright.
Pompey were struggling to find any rhythm going forward in the early phase of the contest but found some fluency with some decent build-up play before Fogden’s industry won him possession inside the box, only to see his cross cut out at the near post.
The Dons had looked the much more dangerous side and they took a deserved lead in the 26th minute through Fitzpatrick.
Nick Awford lost a 50-50 in midfield against Beere 30 yards from goal, Fitzpatrick latched on to the midfielder’s pass and his low shot found its way past Poke, who could only get a foot to it.
Wimbledon then doubled their advantage seven minutes later as Beere capitalised on some defensive hesitancy with an enterprising run and found the net with another low shot that was too powerful for Poke.
That appeared to finally jolt Pompey into life and they registered their first shot on target 11 minutes before the break when Andy Barcham tried his luck from the edge of the box, but it was an easy save for Dons keeper Ross Worner.
But seconds later, Fogden should have pulled one after finding space in the box, only for Worner to deny him with his legs when a dinked finish would have left the keeper with no chance.
With Pompey enjoying a good spell of pressure, Awford forced a good save from the keeper when his deflected 30-yard drive had Worner scrambling low to his right to keep it out.
And Conor Chaplin twice went close in the closing minutes of the half, first from a tight angle as his shot was beaten out before his poked shot from inside the box appeared to be tipped round the post by the keeper, only for the referee to point for a goal-kick.
The game was effectively over as a contest just five minutes into the second half as WImbledon extended their lead with the speedy Fitzpatrick again proving to be the difference.
The winger outpaced the Blues defence in the inside right channel and his angled drive found the far corner, even though Poke got a hand to it.
He completed his hat-trick soon afterwards in similar fashion with another bright run into the box and a smart finish across Poke that put the result beyond any doubt at all.
Substitute Davies at last gave Pompey something to smile about when he pulled one back soon after coming off the bench with Worner at fault in the build-up but it proved nothing more than a consolation.
POMPEY RESERVES: Poke, Webster, Ertl, Chorley, Barcham (Davies, 72), Awford, Atagana (Granger, 80), Fogden (Nilsen, 72), Haunstrup, Westcarr, Chaplin. Unused sub: Bass.