Following a midweek defeat to Blackpool, Pompey were faced with their first true test of the season when fellow promotion favourites Doncaster came to Fratton Park.
It was a test they would ultimately fail as fans were still streaming into the ground when David Forde rushed out of his goal and was rounded by John Marquis who slotted the ball into an empty net.
Some more terrible defending allowed Andy Williams to get onto a flicked on header from a long ball to double Donny's advantage. Although one of their defenders needlessly kept Gareth Evans' cross in play which allowed Carl Baker to slam home the loose ball, there was to be no equaliser and Portsmouth were beaten at home for the first time in the season.
Back-to-back defeats had fans once again questioning Paul Cook's credentials and whether he was the man capable of getting Pompey promoted but he would have to wait to answer those questions as the next match was in the pointless Checkatrade Trophy.
A post war record low crowd of just 1,355 turned up at Fratton Park to watch a weakened Pompey side take on Reading's B team, with Pompey once again being fined £5,000 for the changes to the side.
Curtis Main scored twice to ensure the match finished in a 2-2 draw which meant a bonus point would be awarded to the side that won a penalty shootout, such is the farcical nature of this stupid competition.
Liam O'Brien produced a couple of excellent saves in the shootout but he was beaten too many times and the Royals reserves won. Again, nobody really cared.
Pompey fans were desperate to get back to league action and next up was a visit to Brisbane Road to take on bogey team Leyton Orient, who were struggling at the bottom of League Two and had just hired Alberto Cavasin as their new manager.
The visitors should have taken the lead when a superb instinctive flicked finish from Conor Chaplin was incorrectly disallowed for offside in a game Paul Cook's men dominated. The goal would end up coming in an unlikely manner as Pompey scored directly from a corner thanks to Christian Burgess' header and that was enough to win the game.
Portsmouth's next match would be the biggest of the season to date as they travelled to Home Park looking for vengeance and an important three points against Plymouth who were also battling for promotion.
Argyle took the lead thanks to Yann Songo'o's header from a long free kick but Pompey hit back when Kyle Bennett fired in his first goal of the season from the edge the box and it looked like a measure of revenge would be taken when Danny Rose's late volley crashed against the inside of the crossbar and over the line to give the Blues the lead.
However, with the game ticking towards stoppage time, another long ball wasn't dealt with and that led to Connor Smith equalising for Plymouth with a typically late goal which embodied their own season. Pompey would have the last laugh on Plymouth but back then, it was a painful two points dropped.
The following game against Notts County should have been an opportunity to bag a victory but the visitors had other ideas as Adam Campbell was given too much space to turn and curl the ball into the top corner past Forde.
Chaplin tapped in an equaliser soon after that but it would be the Magpies who claimed all three points as Campbell bagged his second of the match following more atrocious defending. Aaron Collins was sent off for a late lunge on Forde but Pompey were unable to find an equaliser and fell to their second league defeat at Fratton Park.
October ended with a trip to Cambridge's Abbey Stadium and an ugly encounter was settled by a single Chaplin goal as he sent a looping header beyond the U's keeper from Burgess' long ball.
Pompey were forced to play the last half an hour with ten men as Amine Linganzi was sent off for a dangerous challenge on Conor Newton but they held firm to record an important victory which proved they had the steel to grind out results away from home.
That result saw Portsmouth hover just outside the automatic promotion places and fans believed that with some more consistency at Fratton Park, the goal of winning promotion could be achieved even if the title was an afterthought.