A youthful Pompey XI beat AFC Stoneham 5-4 on penalties to book their place in the quarter-finals of the Hampshire Cup.
Alfie Bridgman had earlier fired the Blues into the lead and that looked to be enough to see off their more senior Wessex League opponents.
Duarte Martins levelled right at the death, however, to ensure spot-kicks would be required to see who earned a trip to Farnborough in the next round.
And the visitors held their neve by netting five of their six efforts, with substitute Jamie Howell dispatching the decisive penalty.
With the first team having beaten Burton in the league the previous day, it was a team full of under-18s players who took to the pitch for the visitors.
Liam Daish was in charge from the dug-out, with Blues boss Danny Cowley, chief executive Andrew Cullen and academy manager Greg Miller watching from the stands.
AFC Stoneham certainly had a physical advantage and were first to threaten when a cross from the left was nodded into Toby Steward’s arms by Jamie Bulpitt.
Bridgman then did well to find Gabriel Kamavuako at the other end, with the winger firing into the side netting from an acute angle.
The hosts came close to breaking the deadlock as Jim Orvis’ cross-shot was dipping under the bar, only to be palmed away by a back-pedalling Steward.
Duarte Martins then managed to get on the end of an Orvis delivery, but headed over from just a few yards out.
But it was the Blues who forged ahead on 21 minutes, as Harvey Hughes combined well with Harry Jewitt-White to tee-up BRIDGMAN, who slotted calmly into the bottom corner.
There might have been an opportunity for Dan Gifford to double the lead, but Tom Parker-Trott leapt on a ball that ran loose in his area.
Pompey were looking tidy in possession and certainly not overawed against their more senior opponents.
But AFC Stoneham had one chance to level before the break, with Martins blazing over after being found unmarked in the box.
Half Time: AFC Stoneham 0 Pompey 1
Steward ensured the Blues remained in front once the action restarted, getting down to his left to deal with a thumping Ben Clarke header.
Kamavuako then twisted and turned his way into the area, but could only hit a scuffed effort straight at Parker-Trott.
But the Purples were posing more of a threat and substitute Cal Laycock found space in the box, only to get his attempted lob totally wrong and see the ball fly high and wide.
Kaba was then forced to turn the ball behind just past the hour following a misjudgment from Steward.
The keeper certainly redeemed himself from the resulting corner, however, somehow stopping Will Wiseman’s header from creeping into the bottom corner.
And when Scott Hills sent a teasing low delivery across the face of goal, somehow the ball evaded everyone.
Pompey went back on the attack, but dangerous balls into the box by Bridgman, Kamavuako and Jack Fox could not be met by a red-and-black-shirted team-mate.
The home side pushed for a late leveller and Steward again had to be at his best to deal with Laycock’s low strike.
And they did score right at the death, as Martins headed home an Orvis cross to ensure the tie would head to penalties.
Full Time: AFC Stoneham 1 Pompey 1
Gifford, Harvey Hughes, Elliott Simpson and Jewitt-White all converted from 12 yards, but Bridgman’s shot was saved.
Martins rattled the crossbar for the hosts, however, and the ball would not bounce over the line, so the shoot-out went into sudden death.
Keeper Parker-Trott then blazed his effort high over the crossbar, leaving Howell to slot home the crucial spot-kick.
AFC Stoneham (4-4-1-1): Parker-Trott; Kerton, Clarke, Wiseman, Barnes (James 87); Orvis (c), Bulpitt (Laycock 49), Banbridge, Hills; Penny (Thomson 72); Martins
Goals: Martins 90
Booked: Martins
Subs not used: Godwin, Clements
Pompey (4-1-4-1): Steward; J.Fox (Laidlaw 85), Kaba (c), Dockerill, Hughes; Simpson; Kamavuako, Jewitt-White, Payce (Howell 77), Bridgman; Gifford
Goals: Bridgman 21
Subs not used: Spurway, Bosaka, Hurst
Referee: James Robinson
Attendance: 657