Pompey began their Checkatrade Trophy campaign with an entertaining 3-3 draw against Fulham’s under-21 side at a sparsely-populated Fratton Park.
But it was the visitors who claimed a bonus point after triumphing 4-2 in the resulting penalty shoot-out.
Stephen Humphrys gave the Londoners an interval lead, while the goals rained in following the interval.
Jamal Lowe and Kal Naismith turned the match around before George Williams levelled from the spot.
But there was still time for Lowe to fire the Blues back into the lead, while Elijah Adebayo’s strike then ensured penalties.
Kenny Jackett made seven changes to the side that were beaten at Oxford in the league on Saturday.
First year scholar Joe Hancott – at the age of just 16 years and 161 days – was handed a debut at left-back.
The competition rules also allowed Lowe to feature, despite being in the middle of his three-match suspension.
Gareth Evans, Jack Whatmough, Adam May and Naismith were the only players who started at the Kassam Stadium to keep their place.
There were not too many inside Fratton Park to watch an entertaining first half that saw chances at both ends of the pitch.
A lovely passing move from the hosts ended with May drilling in a low shot that was well held by Cottagers keeper Magnus Norman.
Alex Bass then juggled a dangerous Jon Dagur Thorsteinsson free-kick that was whipped in from wide on the left.
Williams also saw an effort well blocked by Whatmough before Jerome Opku headed a corner straight at Bass.
The action quickly switched from one end of the pitch to the other and Curtis Main glanced a header wide from Ben Close’s cross.
But it was Fulham who broke the deadlock on 21 minutes, as Humphrys drilled an angled shot right into the bottom corner.
Bass stopped Thorsteinsson from doubling their lead moments later, getting down to his right to push the midfielder’s effort clear.
Pompey were soon on the hunt for an equaliser, however, and Close’s snap-shot was deflected inches past the post.
The hosts then broke quickly from a Cottagers corner and Main released Hancott, whose fierce strike was well saved by Norman.
Whatmough wasted a fantastic opportunity to score late in the first half when he was left free to meet May’s delivery, only to send the ball wide.
Half Time: Pompey 0 Fulham U21 1
Pompey had a great chance to draw level just after the interval when May slipped a pass through to Naismith in the box.
The Scottish forward elected to try to squeeze a shot inside the keeper’s near post, but Norman managed to divert the ball behind.
LOWE did find the net on 54 minutes, though, picking up Main’s neat back-heel and angling a shot into the net.
And the match was turned on its head moments later, as Evans whipped in a cross from wide on the right that NAISMITH fired home.
Pompey were not ahead for long, though, as Bass needlessly brought down Williams and referee Antony Coggins pointed to the spot.
It was Williams who stepped up to take the penalty and hammered it straight down the middle to make it all square.
But the goals kept coming and the Blues were back in front on 66 minutes when Evans’ attempt was deflected into LOWE’s path and he swivelled before firing an unstoppable shot past Norman.
Substitute Kyle Bennett almost gave the hosts a cushion, only to see his long-range effort rattle the crossbar.
And Fulham ensured there was more drama in a topsy-turvy encounter when Adebayo slammed home, despite furious Pompey appeals for offside.
That ensured both sides took one point, with a penalty shoot-out held to see who would claim the bonus one on offer.
Fulham took four in the new ‘ABBA’ format and scored them all, but while Conor Chaplin and Bennett both found the net, Norman saved from Naismith and Evans.
Pompey (4-3-3): Bass; Evans (c), Davies, Whatmough, Hancott; May, Baker (Bennett 60), Close (Talbot 76); Lowe, Main (Chaplin 68), Naismith
Goals: Lowe 54, 66, Naismith 57
Subs not used: McGee, Burgess, Haunstrup, Kabamba
Fulham U21 (4-4-2): Norman; Sessegnon, Davies (c), Opoku (Harris 76), Kavanagh; Humphrys, O’Riley, Kait (Kwietniewski 79), Thorsteinsson; Williams, Adebayo
Goals: Humphrys 21, Williams 62 (pen), Adebayo 82
Subs not used: Ashby-Hammond, Nabay, Andrason, Elstone, Pearce
Referee: Antony Coggins
Attendance: 1,520 (62 away fans)