The Pilgrims were up against it after first half goals from Jermaine Johnson, Gareth Owen and David Eyres put The Latics firmly in control at the halfway point.
Paul Wotton did pull one back, but he was then dismissed before Paul Murray put the seal on a fine win with a fourth after 67 minutes.
Robert Clare stopped QPR from another three-point haul after his 58th minute equaliser cancelled out Martin Rowlands's early opener to give Stockport County a 1-1 draw.
Bristol City came from two-down to level matters a two apiece at Kenilworth Road against Luton, however Keith Keane sealed the drama with a dramatic winner.
Steve Howard and Emmerson Boyce put The Hatters in the driving seat, before Christian Roberts and Daniel Coles brought the visitors level.
While a point was not good enough for Danny Wilson's men, he would have taken it before Keane nipped in to steal a 3-2 victory.
Swindon Town closed to within just three points of the third place Robins after a 3-0 away success over already relegated Wycombe Wanderers.
Goals from Stefani Miglioranzi, Sam Parkin and Andrew Gurney, the latter from the penalty spot, sealed a comfortable win for Town.
Hartlepool United moved six points clear of Port Vale following a 4-0 thumping over Notts County.
Richie Humphries fired the side ahead just before the break with second half efforts from Adam Boyd (2) and Hugh Robertson completing the win.
Port Vale lost ground on the play-off pack after being held at home by Chesterfield. Ian Evatt had the visitors ahead, however Billy Paynter earned a point with a 74th minute leveller.
Bournemouth's play-off hopes took a pasting after a 5-1 thrashing by Tranmere Rovers.
Goals from Gary Jones (2), Danny Harrison and Paul Hall had Rovers four-up before a Graham Allen own goal pulled one back.
The visitors restored their four-goal cushion when David Beresford scored after 81 minutes to complete the rout.
Blackpool picked up a fine 4-1 win against Sheffield Wednesday at Bloomfield Road in Division Two's early game on Saturday.
The Seasiders kept their fans entertained throughout, and after John Murphy had given them a 10th minute lead, doubled their advantage on 26 through Mike Sheron.
Wednesday got themselves back in touch when Chris Brunt dragged one back before half time.
However, it was Blackpool that added to their score - with both Sheron and Murphy grabbing second goals to wrap up the scoring.
Leon Knight's penalty after just 11 minutes lifted Brighton to a 1-0 win over Peterborough United, while Phil Jevons's late penalty sank Rushden & Diamonds, who had Robert Duffy sent off.
Goals from Stewart Talbot and Jay Tabb gave Brentford a 2-0 victory over Barnsley a much-needed points boost in their battle against the drop.
Colchester United secured their 15th league win of the campaign after a 3-1 victory over Wrexham.
Hector Sam equalised after Gareth Williams opened the scoring, however further efforts from Greg Halford and Scott McGleish settled the contest.
Click below for match summaries:
Barnsley 0-2 Brentford
Blackpool 4-1 Sheff Wed
Bournemouth 1-5 Tranmere
Brighton 1-0 Peterborough
Colchester 3-1 Wrexham
Grimsby 1-0 Rushden & D'monds
Hartlepool 4-0 Notts County
Luton 3-2 Bristol City
Oldham 4-1 Plymouth
Port Vale 1-1 Chesterfield
QPR 1-1 Stockport
Wycombe 0-3 Swindon
Click here for the latest Second Division table.
