Alfie McCalmont scored for the third time in four games but it wasn’t enough to prevent Latics from slipping to defeat at Leyton Orient.
Individual mistakes cost Keith Curle’s side dearly as the visitors conceded twice in the first half to leave the capital empty-handed despite an encouraging overall performance.
Creating numerous chances and controlling large parts of the play, errors at the back proved to be their undoing.
McCalmont struck in spectacular fashion midway through the second period to give Latics hope of a comeback but despite having several sights of goal in the closing stages, they were unable to repair the damage.
Having registered his first win as Latics boss in midweek, Curle made one change from the victory over Exeter City, as Harry Clarke returned to the side from injury.
Unfortunately, it was Clarke’s slip which gifted the home side an eighth-minute opener, as his attempted pass back to goalkeeper Laurie Walker was intercepted by Conor Wilkinson, who seized on the mistake with a clinical angled finish.
Despite the concession of an early goal, Latics were undeterred in their play. Davis Keillor-Dunn was inches away from an Andrea Badan cross when directly in front of goal, while the in-form McCalmont dragged a shot wide after great work to weave his way to the edge of the area.
Conor McAleny also displayed excellent footwork to engineer the visitors’ best chance of the half, creating an opening before placing an angled shot across the dive of Lawrence Vigouroux, only for the ball to cannon off the post.
It remained an open game, with Walker saving from James Brophy, Wilkinson and Danny Johnson, before Latics conceded again two minutes before half-time.
A slip from Nicky Adams presented Dan Kemp with a chance to turn and rifle an unstoppable finish into the bottom left-hand corner.
To their credit, Latics continued plugging away and their good football was rewarded when McCalmont struck in spectacular fashion, curling a shot beautifully past Vigouroux from outside the area.
The visitors should really have completed the comeback, as Keiller-Dunn failed to find a finish after Adams had linked with Badan, before the attacker went close again and McAleny then shot over.
Latics must have thought they had equalised in stoppage time when Raphael Diarra’s header from a McCalmont corner flashed over the bar before Piergianni sent the ball wide as the visitors were unable to capitalise on their late pressure.
Oldham Athletic: Walker, Clarke, Piergianni, Whelan, Keillor-Dunn, Jameson, McAleny, Badan (Fage 70), Hilssner (Diarra 55), Adams (Borthwick-Jackson 81), McCalmont.
Subs not used: Bilboe, Ntambwe, Sutton, Vaughan.
Leyton Orient: Vigouroux, Widdowson, Cisse (McAnuff 59), Happe, Clay, Wilkinson (Dennis 59), Kemp, Brophy, Akinola, Turley, Johnson (Abrahams 84).
Subs not used: Sargeant, Ling, Coulson, Dayton.
Referee: Darren Drysdale