Oldham's automatic promotion dream took a battering at Boundary Park as Plymouth gave their play-off hopes a massive lift.
Micky Evans bagged the winning goal after 39 minutes and Argyle held on comfortably for one of their best results of the season.
Manager Paul Sturrock is aiming for a second successive promotion and was delighted with the way his team bounced back from the midweek defeat at struggling Huddersfield.
He said: "We needed to get back on the rails and our first half showing was particularly good.
"Micky Evans caused mayhem and Oldham couldn't handle him in the air, plus he took his goal very well.
"We gave ourselves a few problems in the second half because we didn't always splay to our plan but the keeper still didn't have much to do.
"The lads can have a break until Tuesday and they deserve it. I'm not talking about promotion, in fact I'm more pleased that we are becoming sure of not going down." Oldham boss Ian Dowie was less than impressed after his team, who are still unbeaten away, lost for the sixth time on home turf.
He said: "Our record here isn't good enough and it's something the lads have to address as a matter of urgency.
"Fair play to Plymouth but we didn't have enough guile or invention to break them down and we weren't brave enough around the box.
"It isn't nice having to go in where it hurts but it's part of the job and our strikers didn't have it.
"They need more hunger and I hope they will be very fired up for a big local derby at Stockport next week." Plymouth started well and could have had a fourth minute penalty for handball, while Marino Keith had a shot blocked after poor defending.
Oldham's Wayne Andrews blazed a good chance off target before Plymouth went close through Paul Wotton whose shot from fully 40 yards was only just scrambled out by the keeper.
The winner was slotted into the bottom corner by Evans seven minutes before the break from 16 yards, after he had brushed aside his marker.
Oldham only went close to equalising through Andrews, but his overhead kick was cleared off the line by Wotton.
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