Dion Donohue grabbed the only goal of the game as Pompey progressed in the Checkatrade Trophy.
The utility man celebrated his return from injury with a confident first-half finish as Kenny Jackett’s side grabbed a 1-0 win at Crawley.
That sees the Blues through to the second round of the much-maligned competition as they returned to winning ways after their first league defeat to Gillingham.
Joe Mason’s woeful late penalty miss had no impact as he blazed way over the top.
Pompey handed a debut to 16-year-old Haji Mnoga, with the former Trafalgar School pupil becoming the second youngest player in the Blues’ history.
And the local lad delivered a confident and composed display at right-back, which was one of the night’s big positives.
Louis Dennis was also handed his bow as Donohue came in for his first appearance of the campaign.
There was little in the way of chances for either side until Dennis angled a 20-yarder not too far wide in the 29th minute.
The opener arrived eight minutes later when Gareth Evans picked out Joe Mason and he in turn picked out Donohue, who skipped down the left, checked on to his right foot and arrowed an assured finish past Red keeper Yusuf Mersin.
Brian Galach missed a great chance to level four minutes after the restart when he slotted an unopposed finish wide from 12 yards, after David Sesay beat Donohue down the right.
The response came from Ben Close, who glided a shot not too far over from just inside the box.
Josh Doherty put a dangerous ball across the face of goal in the 63rd minute which no red shirt could tap in.
Tarryn Allarakhia sailed a late 25-yarder not too far past Luke McGee’s upright and then came Mason’s terrible penalty miss as he blazed over, following Mark Randall’s foul on Anton Walkes.
That meant little, however, as Pompey held on to secure the win and advance to the second round.