Scott Taylor took his goal tally to 20 for the season as Blackpool pulled off their second win of the campaign at Boundary Park.
The Seasiders had already won 3-2 in league combat but they stepped up on that performance to extend their current run to seven victories in eight games.
Oldham had no shortage of chances but Blackpool showed them the way to FA Cup glory through Taylor's treble, Keith Southern and Leam Richardson.
Goals by John Eyre and Jermaine Johnson, his first on loan from Bolton, were little consolation for an Oldham team who are struggling for form.
Taylor put them behind within two minutes of the start as he ran 20 yards into the box and put a low shot into the corner.
His second arrived on 20 minutes as a neat throughball put him in a one-against-one with keeper Leslie Pogliacomi who was given no chance as the ball slid between his legs from 12 yards.
Blackpool were 3-0 up five minutes later thanks to a quick break from defence which was completed by Southern when he fired through a chaotic defence from eight yards.
Oldham managed to pull one back just past the hour mark as Ernie Cooksey headed across goal and makeshift striker Eyre just beat visiting keeper Lee Jones to the ball for a simple finish.
If Oldham entertained any hope of a recovery it was soon wiped out when Martin Bullock crossed from the right and Will Haining intercepted with his hand.
Taylor's penalty was saved by Pogliacomi who dived to his right but the rebound fell nicely for Blackpool's hero and he tucked in from close range.
The fifth came after 73 minutes and was an absolute beauty - Richardson chested the ball down and his volley from fully 25 yards whistled an inch inside the post.
The final act of a dramatic afternoon came in stoppage time as Johnson reached a Danny Boshell pass and reversed his shot into the far corner from ten yards.