Dion Donohue netted his first Pompey goal to secure victory at Crawley in an uneventful Checkatrade Trophy contest at Broadfield Stadium.
But the result was enough to ensure that the Blues have reached the knockout stages with a group game to spare.
There was not a lot for either goalkeeper to do on a mild evening in Sussex and Donohue’s effort was comfortably enough to secure all three points.
Joe Mason could even afford to miss a late penalty in a game that will not live long in the memory of anyone present – bar Donohue, perhaps.
Kenny Jackett made nine changes from the side that finally suffered a league defeat to Gillingham at the weekend.
Gareth Evans – who wore the captain’s armband – and Ben Close were the only players to keep their places.
There were debuts for Louis Dennis and 16-year-old academy full-back Haji Mnoga, while a fit-again Donohue made his first appearance of the season.
Meanwhile, another member of Pompey’s youth set-up, midfielder Freddie Read, was an unused substitute.
Both sides took a while to grow into the game, with clear-cut chances at a premium at both ends throughout the first half.
A shot from Tarryn Allarakhia flew straight at Luke McGee, while the keeper also dealt with David Sesay’s deflected drive.
Then when a George Francomb delivery was only partially cleared, Panutche Camara and Dannie Bulman both had efforts blocked in quick succession.
There were a few crosses for Crawley to deal with at the other end of the pitch, but nothing that the visitors could capitalise on
Dennis did try his luck from the edge of the box, although the ball flew harmlessly wide of Yusuf Mersin’s post.
There was a scare when Evans lost possession inside his own area, although the skipper did well to win it back.
And Pompey went straight up the other end to break the deadlock, with Mason feeding DONOHUE, who cut in from the left and arrowed home a neat finish.
Crawley Town 0
Jackett replaced Evans with Matt Clarke at the start of the second half, as he matched the hosts by playing with three at the back.
But the Reds should have been level soon after the restart, with Sesay doing the hard work by beating Donohue down the right.
He squared for an unmarked Brian Galach, but the striker somehow side-footed his shot wide from 12 yards.
Close was not far away from making him pay for his profligacy, with a trickier attempt that flew narrowly over.
It was still not proving to be a game full of excitement, however, with Pompey content to play some patient passing football.
Josh Doherty had an opening for Crawley when he sent the ball into the danger zone and it evaded everyone to roll inches past the post.
Jackett made his final two changes just past the hour mark, as Mnoga and Donohue were withdrawn for Ben Thompson and Tom Naylor, with the latter slotting into defence.
The visitors tried to make sure of the victory and Close’s shot was gathered by Mersin after Anton Walkes had headed down Clarke’s free-kick.
Thompson’s low centre for Mason was just about intercepted, while Clarke nodded a corner wide as the match wound down.
Allarakhia sent a 25-yard thunderbolt fizzing narrowly wide, as the Reds tried their best to force a draw.
But Mason should really have wrapped things up for Pompey from 12 yards after Walkes had been tripped in the box by Mark Randall.
Referee Tim Robinson pointed straight to the spot, but the striker blazed his penalty high over the bar.
Crawley (3-1-4-2): Mersin; Francomb, McNerney, Vincelot; Bulman (c); Sesay, Allarakhia, Camara (Randall 61), Doherty; Poleon, Galach (Maguire 58)
Booked: Vincelot, Randall
Subs not used: Morris, Young, Connolly, Payne
Pompey (4-2-3-1): McGee; Mnoga (Naylor 65), Burgess, Walkes, Haunstrup; Close, Rose; Evans (c) (Clarke 46), Dennis, Donohue (B.Thompson 64); Mason
Goals: Donohue 37
Subs not used: MacGillivray, Read, Pitman, Hawkins
Referee: Tim Robinson