A first-half brace from loan capture Aaron Wilbraham secured a 2-1 victory for Oldham to heap more pressure on bottom-of-the-table Stockport County at Edgeley Park.
The Latics held on for their first win in nine games against Sammy McIlroy's struggling side.
This local derby relegation tussle got off to a blistering start when John Eyre thumped a cracking 25-yard shot against the Stockport crossbar inside two minutes and David Eyres disappointingly fired the rebound wide from just 10 yards.
Oldham were in almost total control early on and they deservedly went ahead on 13 minutes. Veteran Eyres played the ball into new loan man Wilbraham - an ex-Stockport favourite - and he turned Lee Cartwright before drilling home a low shot.
Basement side Stockport finally made some inroads midway through the first half and they were unlucky on 22 minutes when Rickie Lambert's goal bound free-kick was diverted wide by the heel of Luke Beckett.
Marc Bridge-Wilkinson was denied by a superb save from Oldham goalkeeper Les Pogliacomi, while at the other end Eyres should have buried a header from close range.
But Oldham did go two-up on 40 minutes and it was that man Wilbraham again who curled home a sweet shot following a neat one-two with Kevin Betsy.
The home fans were stunned, but just three minutes later Bridge-Wilkinson rifled home through a sea of legs from outside the box.
Reducing the deficit gave Stockport some heart, and either side of the hour mark Warren Feeney and Bridge-Wilkinson both came close to levelling matters.
The home side remained on the offensive, but despite late efforts from Feeney and substitute Stuart Barlow, Oldham managed to hang on for a crucial victory.