Sheffield United's push for promotion to the Championship could be hindered as they trail Oldham Athletic at Bramall Lane.
A frantic start almost saw the Blades lead after 35 seconds when Jose Baxter's strike was met by a flying stop from Latics keeper Paul Rachubka.
The visitors, who started the game in ninth place in League One, could have taken the lead themselves when Jabo Ibehre's effort was tipped away before Genseric Kusunga headed wide moments later.
Oldham then took the lead on 16 minutes as Daniel Johnson crossed for Jonathan Forte, who made no mistake in beating United keeper Mark Howard.
The home side's best opportunity to get back on terms came on 31 minutes when Stefan Scougall's drive from the edge of the box was inches wide.
However, the Latics were almost further ahead moments before the interval when Danny Philliskirk's long-range effort was tipped away by Howard.
