A late Everton goal condemned Pompey Reserves to a 2-1 defeat in their opening Premier League Cup group match at Westleigh Park.
It looked like the spoils would be shared when Nathan Broadhead’s opener was cancelled out by Theo Widdrington’s penalty following a foul on Dan Smith.
But, with the end fast approaching, Shayne Lavery netted for the visitors to break the Blues’ solid resistance.
Defenders Drew Talbot and trialist Thomas Juel-Nielsen were the senior figures in an otherwise youthful line-up that included five academy players.
And Everton tried to make the most of their opponents’ inexperience by attacking them from the start.
It took a perfectly-timed tackle from Talbot to stop German striker Anton Donkor in his tracks in the opening seconds.
Broadhead then collected a cross-field pass from skipper Jose Baxter and thumped a fierce 25-yard shot against the post.
Pompey were struggling to create much at the other end, although it took some strong defending from Matty Foulds to halt Jez Bedford’s charge.
The Toffees were posing more problems, though, and Donkor's dangerous cut-back had to be scrambled behind.
Alex Bass then charged to the edge of the box to beat Bassala Sambou to Beni Baningime’s threaded pass.
But Sambou did have an opportunity to shoot midway through the half and his effort dipped narrowly over the bar.
Everton appeared to be moving closer to a goal and Donkor’s fierce strike would have tested Bass if Talbot’s head had not diverted the ball off target.
The striker did have the ball in the back of the net moments later, but he was clearly stood offside when converting Nathangelo Markelo’s delivery.
Half Time: Pompey 0 Everton 0
Pompey looked more dangerous after the restart and Talbot’s dangerous pass across the face of goal had to be hacked clear by Con Ouzounidis.
But Everton were soon back on the attack and hit the woodwork for a second time, with Sambou’s effort striking the crossbar.
There were half-hearted appeals from the hosts for a penalty when the ball bounced up and hit Ouzounidis on the arm, but they were quickly dismissed by referee Adrian Quelch.
It then took a crunching tackle by Markelo to stop Blues winger Smith from getting free down the left.
But it was the Toffees who finally forged ahead on 72 minutes when Broadhead met Luke Garbutt’s cross with a header that left Bass helpless.
Pompey were behind for a matter of seconds, though, and when Markelo was punished for a nudge on Smith in the box, WIDDRINGTON stepped up to slam his penalty into the top corner.
They might have then gone ahead, but Louis Gray saved brilliantly at the feet of Leon Maloney, who had only just left the bench.
Instead it was Everton who benefitted from a late twist that was cruel on the hosts, as another Garbutt delivery was nodded back by Antony Evans for Lavery to neatly slot home.
Pompey (4-2-3-1): Bass; Oxlade-Chamberlain, Talbot, Juel-Nielsen, Hancott (Dandy 86); Read, Widdrington (c); Chandler, Bedford (Maloney 79), Smith; Mayes (Lethbridge 74)
Subs not used: Collins, Casey
Everton (3-4-3): Gray; Denny, Ouzounidis, Foulds; Markelo, Baningime (Evans 74), Baxter (c) (Lavery 56), Garbutt; Broadhead, Donkor (Byrne 65), Sambou
Subs not used: Hilton, Henen
Referee: Adrian Quelch