Shot-shy Cobblers failed to score a goal for the fifth game in succession as they exited the Checkatrade Trophy, going down 2-0 at Portsmouth.
Goals either side of half-time from Gareth Evans and Stuart O'Keefe proved enough for Pompey to progress, with the home side deserved winners.
The Cobblers did have their moments, especially in an enterprising spell of play at the start of the second half, but the bare fact is they once again failed to find the target.
An extra concern for Jimmy Floyd Hasselbaink will be the fact that striker Chris Long had to be withdrawn at half-time with an ankle problem. The Town boss will be keeping his fingers crossed it's nothing serious.
Hasselbaink made three changes to the team that drew 0-0 against Bury in Sky Bet League One last weekend.
Matt Grimes was suspended after picking up two bookings in the group stages, and was replaced by Lewis McGugan, while the fit-again Sam Hoskins came in for Shaun McWilliams, who missed out due to a slight groin strain.
David Cornell started in goal with Matt Ingram given the weekend off, meaning Luke Coddington was named on the bench.
John-Joe O'Toole (ankle) and Daniel Powell (hamstring) are still not match fit, and did't travel to the south coast.
With three sides of Fratton Park closed, it was a slightly surreal atmosphere to proceedings as the players came out for the game, but the fact both Hasselbaink and Portsmouth boss Kenny Jackett named virtually the strongest teams available to them was a measure of how seriously they were taking thing, even if the fans weren't.
Both sides struggled to create chances and retain meaningful possession in the early stages, with a couple of pot-shots at goal each, before the game belatedly exploded into life after 32 minutes.
That was when former Cobblers midfielder Danny Rose, who stood out in the first half, had the first shot in anger, the ball fizzing across goal and wide, before the ex-Oxford United man then turned provider, on 40 minutes.
His long pass over the top was latched on to by Evans, who composed himself and got a strong shot away, but Cornell produced an excellent save to his right to touch the ball around the post.
From the resultant corner, Town broke quickly, with Hoskins picking the ball up in his own half and driving into the Pompey final third.
He then slipped a pinpoint pass into Long who had ran beyond the Pompey defence, but the angle was against the loan striker who saw his low shot saved by Luke McGee.
From the corner - Pompey took to the lead!
McGugan delivered the ball into the box and after a scramble, Ash Taylor's attempted pass out wide to Matt Crooks was intercepted, and Pompey were off, breaking at speed.
The ball eventually fell to Chaplin on the left side of the penalty area, but instead of shooting he lifted a pinpoint cross to the far post where an unmarked Evans was on hand to head home past an exposed Cornell.
Long, who had picked up an ankle injury, was taken off at half-time and replaced by Sam Foley, who went to left midfield, with Crooks moving up front.
Town started the second half well, and were so close to an equaliser when Taylor rose highest to meet a McGugan free-kick, but his header was brilliantly save my McGee diving low to his right.
Pompey responded and weathered the storm for 10 minutes or so, and started to threaten again themselves, doubling their lead of 56 minutes.
It was all too easy as Nathan Thompson on the right laid the ball into the path of the unmarked O'Keefe, and from 12 yards out he calmly rolled the ball into the bottom corner of the net.
Despite that setback, Town were still looking a threat at the other end, and Regan Poole sending a sweet 25-yard strike just inches wide, but as the game wore on the home side took more and more control.
Indeed, Pompey should have extended their lead on 77 minutes, but Drew Talbot dragged his shot wide from 10 yards after being set up by Chaplin when he should have scored.
That was a relief for Taylor, who had gifted Chaplin possession 25 yards from his own goal.
Cornell then pulled off an excellent double save from Curtis Main and then Thompson as Pompey threatened to rub the Cobblers' noses in it, but it stayed 2-0.
The result means the Cobblers are now out of all the cups, with just the league to worry about for the rest of the season.
Portsmouth: McGee, Rose, Clarke, Burgess, O'Keefe, Main, Lowe, Chaplin, Thompson (89m, Kennedy), Evans, Haunstrup (69m, Talbot). Substitutes not used: Bass, Bennett, May, Casey, Lethbridge
Cobblers: Cornell; Moloney, Taylor, Barnett, Buchanan; Hoskins (64m, Bowditch), Poole (78m, Waters), McGugan, Crooks; Long (46m, Foley), Richards. Substitutes not used: Coddington, Kasim, Smith. McGivern
Referee: Tom Nield
Goals: 41 mins: Evans, 1-0; 59 mins: O'Keefe, 2-0
Attendance: 1,780 (128 Cobblers supporters)