A poor Portsmouth side fell to a dire defeat at Fratton Park courtesy of a Johnny Ertl own goal in a bad tempered match.
Pompey fans will surely remember the name of referee Carl Berry who lost control of the match after sending two men off and angering the crowd with his petulence.
However, in all honesty, you'd be hard pressed to find any Pompey fans who think their side deserved a result today after their poorest performance of the season so far.
Luke Rodgers made way for Jordan Obita in the starting line-up and it was the latter who had Pompey's best chance of the game early on, as the home side dominated the first ten minutes.
Liam Walker sent the on-loan Reading striker clean through on goal but he could only strike the ball straight at keeper Alex Cisak when he had the option of squaring the ball to an unmarked Izale McLeod.
Pompey stuttered after that early flurry with Oldham growing into and taking control of what was not a pretty game due to poor passing and interruptions from the referee.
The visitors should have taken the lead late on in the first half as Lee Croft's corner caused chaos in the box and Mikkel Andersen saved a shot before a second was blocked on the line before the ball was eventually cleared to safety.
You would have thought Michael Appleton would have told his players to wake up after a lacklustre first half but things got worse after the break.
Brian Howard had a quality free kick saved but the counter-attack saw two Oldham players break through the Pompey defence and clearly through on goal, though the hosts were given a major let off when the ball was passed forward to Robbie Simpson who was offside.
Just minutes later Cristian Montano struck the post after being given all the time and space in the world to shoot across goal.
Having blown several great chances to score, Pompey decided to be generous and score for the Latics when Ertl slid Croft's cross from the left past a despairing Andersen and into the back of the net, much to the delight of the 150-or-so Latics fans.
Matters got even worse soon after as referee Berry appeared to make two huge blunders.
Chris Brown elbowed Jordan Obita who fell to the ground, yet it was the Pompey striker who was inexplicably shown a straight red card.
To further his incompetence, Berry then dismissed Cliff Byrne after consultation with the fourth official. It was difficult to see whether the right man was eventually sent off or not but it was ten on ten for the rest of the match which was played with the background of a very angry home crowd.
Ashley Harris and Rodgers were sent on late to try and rescue something for Pompey but they could not find a breakthrough and fell to a defeat which may well change the entire mood around the club.
Despite the incompetence of the referee, Pompey were slow and struggled to deal with the physical side of Oldham's game which also favoured the dreaded "route one" long ball style of play.
Paul Dickov has moulded a team based on his own image when he was a player; strong, irritating, ugly to watch and a nuisance to play against. But much like Pompey struggled to deal with him in his Leicester days, they struggled with the physical side of his team's game today and need to be wiser.
Oldham will not be the only side to come to Fratton Park and play that way so Michael Appleton needs to get his team to adapt to that quickly if they are to avoid more poor results like this.
The team should cope easier when Kevin Long returns to the side and Josh Thompson is introduced to League One. The two tall, commanding centre backs should improve Pompey's defence, particularly against long balls.
As for the rest of the team, they will need to up the tempo if Appleton is to stick to his passing game and the side will need to gel quickly if yet another relegation battle is to be avoided.
Pompey Player Ratings
Mikkel Andersen: 7 - A couple of good stops when Oldham actually found the target.
Mustapha Dumbuya: 6 - Biggest threat going forward but left defense exposed as usual.
Johhny Ertl: 5 - Debut to forget.
Paul Connolly: 5 - Struggled with the physical Oldham forwards.
Jon Harley: 6 - Did OK.
Liam Walker: 6 - Tried to keep the ball on the floor.
Brian Howard: 5 - Well off the pace.
Darel Russell: 5 - Needs time to settle in.
Jack Compton: 6 - Got a few crosses in.
Jordan Obita: 5 - May have been harshly sent off but did himself no favours with constant shirt tugging and an embarassing dive in the first half.
Izale McLeod: 5 - Never really threatened.
Ashley Harris (Walker 67): 6 - Tried hard.
Luke Rodgers (Ertl 84): N/A - Why didn't he start?