Pompey had to settle for a disappointing 0-0 draw against League Two’s bottom club Northampton Town.
The Blues at least extended their unbeaten run to two games but will be kicking themselves that they were unable to beat a side who are rooted to the foot of the table.
The closest either side came to a breakthrough was through Jed Wallace early in the contest but his speculative effort rattled back off the crossbar.
While Trevor Carson was relatively untroubled throughout, Northampton were certainly no mugs and looked a well-organised outfit.
Although Pompey had the majority of the play after the break, they were unable to find the breakthrough with David Connolly left on the bench until five minutes from time, despite chants from the home fans to bring him on.
But the clear chance failed to materialise as another 15,000-plus crowd were left frustrated.