Rampant Oldham tore up the form book to leave Division Two leaders Plymouth shell shocked.
The Latics hit three goals in eleven first half minutes, resisted heavy pressure and finally sealed one of their most important wins all season.
But referee Mark Cowbourn was the centre of attention with Plymouth left feeling robbed by a string of disputed decisions.
The sending off of Paul Wotton bewildered both managers and Argyle had a goal controversially disallowed when the score was 3-1.
Wotton received his second booking for taking a free kick too quickly and Plymouth caretaker boss Kevin Summerfield branded referee Cowbourn abysmal.
Summerfield said: "I have to give him a mark. What will it be? There will be a nought in it.
"There was no animosity between the teams but he has flashed cards all afternoon and Paul Wotton came off the pitch fuming.
"That said, it is no excuse for our performance because we just weren't good enough." Oldham also had a player sent off for two bookings as Jermaine Johnson was carded for dissent and deliberate handball.
Johnson had put Oldham in front after they survived an early scare when David Norris was denied by keeper Leslie Pogliacomi.
Johnson raced onto a Mark Bonner pass and rounded the keeper before scoring from eight yards.
It was 2-0 when Plymouth failed to defend a set piece and defender Gareth Owen smashed in the loose ball from close range.
And Oldham completed their triple salvo before half time as veteran David Eyres whipped a free-kick inside the near post from out on the left as Plymouth keeper Luke McCormick left too big a gap.
Plymouth hit back after half time as Marino Keith was fouled by Owen for a penalty.
Wotton's kick was saved but he netted from the rebound.
Wotton walked soon after but his side thought they were back in with a chance when Paul Connolly converted a corner only for Mr Cowbourn to award a free kick to Oldham.
Paul Murray completed Oldham's win on 67 minutes as he controlled an Eyre's pass 12 yards out and drilled inside the post with his left foot.