Mike Jones’ late strike was enough to seal a valuable three points against relegation rivals Chesterfield.
After coming on as a second half substite, he produced a piece of brilliance with only 10 minutes remaining to win the game for Latics.
However, the victory did come at a cost as Aaron Amadi-Holloway was stretchered off on the hour mark and Timmy Thiele appeared to have dislocated his shoulder.
Defender Anthony Gerrard returned to the side after missing Saturday’s game through illness.
It was a first half which lacked quality but it was Latics that had the best chances of the half.
However, the game would take a while to come to life as both sides cancelled each other out in the opening exchanges.
Aaron Amadi-Holloway provided the first real bit of quality of the afternoon on eight minutes as he held the ball up well, turned and crossed into the box but it was just ahead of Curtis Main.
As Latics were starting to build up some momentum, the heavens started to open.
Chesterfield’s first shot of the game came on 13 minutes as Gboly Ariyibi fired over from the edge of the box.
Whilst the Spireites went close at one end, Athletic almost took the lead a minute later but Holloway’s volley from six yards went wide of Tommy Lee’s goal.
Matt Palmer, who returned to the side after missing Saturday’s draw against Burton Albion, fired wide from 25 yards after a promising run as Latics continued to pepper Lee’s goal.
Midway through the half it was again Holloway who went close but his header from a Palmer corner again just went wide of Lee’s goal.
A big talking point of the first half came on the half hour mark as Tom Anderson brought down an onrushing Curtis Main as he raced through on goal.
The referee raced over to the central defender and brandished a yellow card, which was probably fair due to the covering men.
Jonathan Forte was proving to be a constant threat down the left hand side and he was the next to go close.
He raced to the byline, took on full back Liam O’Neill and fired across the box but it was inches off Holloway who was lurking at the back post.
As the half was petering to a close, Main tested the palms of Lee from inside the penalty area but he saved well low to his left.
The second half started much the same as the first and it took a while to get going.
Liam Kelly curled over the crossbar on 50 minutes and five minutes later provided a good cross for Forte who headed wide at the back post.
A low point of the game came just before the hour mark as Holloway was stretched off with his leg in a brace.
Jones came on to replace the forward in what turned out to be a superb switch.
The supporters were doing everything to get behind the lads in a game which would be decided by a superb bit of quality.
Substitute Jones picked the ball up in the middle of the park, took on his man and fired an unstoppable strike into the bottom corner to win the game for Latics.
It could have been even better for Athletic as straight from the kick off, Timmy Thiele lobbed Lee from distance but he just got back on his line in time to tip over.
Chesterfield started to pile on the pressure in a bid to get something out of the game with Jay O’Shea instrumental in their attacks.
With a minute remaining he gained space in the box but his shot was blocked by captain Kelly.
Six minutes additional time was signalled by the referee but in the first minute of that, Thiele was forced off with a shoulder injury.
He was replaced by Jake Cassidy as Latics looked to see the game out.
It would prove to be a nervy ending as Chesterfield threw everything forward in a bid to get something out of the game but O’Shea’s shot eight minutes into additional time went over the bar and the referee blew his whistle to signal a massive win for Latics.
Oldham Athletic: Coleman, J.Wilson, B.Wilson, Gerrard, Holmes-Dennis, Dieng, Kelly, Palmer, Forte (Thiele 72’, Cassidy 90+1’), Main, Holloway (Jones 60’).
Subs not used: Cornell, Mills, Croft, Winchester.
Chesterfield: Lee, Hird, Liddle, Ebanks-Blake (Slew 66’), Novak, O’Neill, Campbell-Ryce (O’Shea 56’), Raglan, Anderson, Talbot, Ariyibi (Orrell 83’).
Subs not used: Herd, Humphreys, Chapman, Banks.
Goals: Oldham Athletic (Jones 79’) 1-0 Chesterfield
Attendance: 4,483 (599 visiting supporters)