Poor Walsall struggled for long periods as Oldham went on to complete the double over the Saddlers who slumped to their fourth successive defeat and have now collected just two points from seven games.
Oldham were worthy winners as Walsall were effectively shut out by a solid Latics defence.
Walsall's problems were highlighted in a frustrating goalless first half when Oldham were the more positive in most departments with the young Birmingham player, Neil Kilkenny, often impressive in midfield.
In sharp contrast Walsall were often disjointed. Paul Merson attempted to weld his team together but with little success.
The lack of cohesion was a major handicap and with so many newcomers in the side this was hardly surprising.
On-loan Julian Joachim who was not so long ago was parading his skill in the Premiership with Aston Villa, sadly lacked support and the dismal result was that Walsall were never able to really pressurise Oldham.
In sharp contrast Oldham were generally the more dangerous with Beckett giving debut boy Tony Gerrard a harrowing game.
Beckett, however, was guilty of a bad miss early in the game when he failed to capitalise on a Kilkenny pass.
The shaven-headed Oldham striker later set up the on-rushing Oldham skipper, Dean Holden, who saw his shot on the run saved at point-blank range by Andy Oakes.
Ominously, Oldham were always threatening and only a timely intervention by the promising Gerrard prevented Chris Killen breaking the stalemate.
It was not until the 65th minute that Merson finally linked up with Joachim but the striker shot straight at the advancing Oldham goalkeeper, Steve Mildenhall.
Oldham's vital winner came in the 72nd minute when substitute Jorge Leitao failed to clear a David Eyres free-kick and allowed the livewire Beckett to notch a crucial goal for the Latics.