It took extra-time to separate Pompey from their Premier League club hosts as Swansea under-23s inflicted a 3-0 defeat.
Mikey Harris’ reserves had given an excellent account of themselves in last night’s semi-final clash at the Landore training ground.
Ultimately, it took two goals in eight minutes during the first-half of extra-time to break their Premier League Cup hearts.
Oliver McBurnie pounced on 94 minutes to open the scoring, before George Byers doubled the advantage.
A second for McBurnie on 118 minutes from the penalty spot sealed victory for the hosts to complete a harsh scoreline.
Yet the Blues can reflect on skipper Ben Close’s open-goal miss shortly before half-time as the one that goal away.
In fact it was remarkable neither side netted during normal time with many good chances spurned before the extra 30 minutes.
But it was the Swans’ youngsters who triumphed in extra-time to reach the final of the competition, where they will face Reading.
Harris selected a side containing only Jez Bedford without first-team experience, while Jamal Lowe was notably included.
There was also a first start for Curtis Main at any level since October as he continues to feel his way back following persistent injury issues.
In the opening stages, the hosts’ George Byers’ free-kick posed a threat 20-yards from goal and narrowly finished the wrong side of the post.
At the other end, superb play from Nicke Kabamba saw the striker hold up the ball before spinning and embarking on a strong run at the heart of the Swansea defence.
He then pulled the trigger and delivered a shot which was straight at keeper Gregor Zabret, who gathered comfortably.
The game was proving entertaining and on 20 minutes Brandon Haunstrup’s belligerence down the left paid off to deliver a dangerous cross.
It fell invitingly to Bedford, but his right-foot shot through a ruck of players whistled just past the right-hand post.
Adam May came the closest to breaking the deadlock so far with a strong run and right-footed shot from just outside the box which was inches away from the top corner.
In the 39th minute, Byers struck the right-hand post with Liam O’Brien beaten as Swansea came so close to breaking the deadlock.
Yet it should have been Pompey heading in at the break with the lead, had it not been for an improbable miss by Ben Close.
Lowe’s shot was saved by keeper Zabret, with Close following up to plant a right-foot shot wide of an open net from eight yards.
Within minutes of the second half, McBurnie drove an angled shot past the on-rushing O’Brien and wide of the far post.
Pompey responded with Lowe flighting in a cross from the left which was met with a fierce back-post volley from Main which flew wide.
Still both sides searched for a goal and on 71 minutes Calvin Davies’ right-footed free-kick was brilliantly tipped around the post.
O’Brien then showed his quality by pushing away Adam King’s drive.
The score line remained goalless as the match headed into extra-time.
O’Brien did brilliantly to push Daniel James’ shot onto the crossbar, but he was finally beaten on 94 minutes.
Pompey’s keeper pushed out another Swansea effort, but there was McBurnie to capitalise from close range.
The hosts doubled their lead on 102 minutes, when Byers smartly turned home King’s cross from the right first time.
The scoreline was completed two minutes from time when McBurnie netted from the penalty spot following Whatmough’s foul.
POMPEY: O’Brien, C. Davies, Whatmough, T. Davies, Haunstrup (97 mins, Widdrington), Close, May, Bedford (91 mins, Oxlade-Chamberlain), Main (97 mins, Smith), Lowe, Kabamba. Subs not used; Bass, Mayes.
SWANSEA: Zabret, Reid, Roberts, Maric (103 mins, Evans), K.Davies, Rodon, James, Fulton, McBurnie, Byers (119 mins, Biabi), King. Subs not used: Lewis, Thomas, Plezier