Oldham Athletic suffered a home defeat as Southend United ran out 0-3 winners at Boundary Park.
Theo Robinson fired the Shrimpers into the lead five minutes into the game but Latics had chances to equalise.
Eoin Doyle went close on a number of occasions but could not find the leveller as Southend United led at the break.
Simon Cox added two quick goals early in the second half to kill the game off for the visitors and ensured Latics fell to defeat, ending their six game unbeaten run.
Manager Richie Wellens made two changes to the side which drew 2-2 against AFC Wimbledon at the weekend.
He made one enforced change as Brian Wilson replaced Anthony Gerrard whilst Jack Byrne returned to the starting 11 in place of Tope Obadeyi.
It was a disastrous start for Latics who found themselves behind in the opening five minutes of the game.
After a corner into the box was not cleared, the ball fell to Robinson who was on hand to stab home from close range.
Latics responded with two efforts of their own soon after. Craig Davies flicked into the path of Eoin Doyle but the striker’s effort went wide of the post.
Seconds later, Davies again flicked the ball down but this time to Duckens Nazon who fired wide of the goal.
Southend almost doubled their lead on 15 minutes as Stephen McLaughlin managed to get in front of his defender but Johny Placide saved his effort from 12 yards with his leg.
Latics started to pile on the pressure and could have been level just before the half hour mark.
George Edmundson flicked on Tom Hamer’s long throw, Doyle headed at goal but Mark Oxley managed to make the save on the line. Athletic felt the ball had crossed the line but the linesman said no.
Oxley saved Doyle’s effort from 25 yards minutes later whilst Rob Hunt met a ball into the box but his volley went wide.
Latics thought they had taken the lead minutes before the end of the half as Byrne and Doyle exchanged a one-two on the edge of the box. Doyle met a Byrne cross with an outstretched leg but could not divert the ball on target.
Wellens made a change at the break and brought on Aaron Holloway in place of Davies and Latics were almost level minutes after the break.
It was Byrne and Doyle who again combined on the edge of the box, Doyle shot but Oxley again made the save low to his right.
Despite Latics starting the half strongly, against the run of play, Southend managed to double their lead.
Cox’s initial effort from 18 yards was saved but the ball fell into the striker’s path and he made no mistake from inside the area and Southend led by two.
Two soon became three as Latics again struggled to clear the ball and Cox fired the ball home at the back post to put Southend United three goals ahead.
Latics almost pulled a goal back immediately as Doyle’s cross found Holloway unmarked six yards out but the striker could not convert.
Jonathan Benteke was introduced for his debut on the hour mark as he replaced Ousmane Fane and he almost made an immediate impact.
The striker cut in from the left and curled an effort goalwards but it went wide of the post.
Latics continued to attack despite the scoreline and forced a number of chances.
On 75 minutes, Dan Gardner did well in the middle of the park to win the ball and race into space. He crossed from the left which was met by Doyle who nodded back to Byrne but his effort was blocked.
A minute later, Gardner again delivered the ball into the box which Byrne met but the midfielder’s effort was blocked.
Placide had to be alert to tip a free kick on to the post on 82 minutes as niggly bookings followed for Doyle and Byrne.
Latics continued to attack until the final whistle but unfortunately could not find a way past a stubborn Oxley.
When they did find a way past him, substitute Gevaro Nepomuceno fired against the post on a night Latics will hope to quickly forget.
Oldham Athletic: Placide, Wilson, Edmundson, Hamer, Hunt, Fane (Benteke 60’), Gardner, Byrne, Nazon (Nepomuceno 83’), Doyle, Davies (Holloway 46’).
Subs not used: De La Paz, Stott, Pringle, Obadeyi.
Southend United: Oxley, Cox, McLaughlin (Gard 90+3’), Yearwood, Mantom, Harrison (McGlashan 83’), Demetriou, Kyprianou, Robinson (Ladapo 69’), Bwomono, White.
Subs not used: Kightly, Fortune, Bishop, Mitchell-Nelson.
Goals: Oldham Athletic 0-3 Southend United (Robinson 5’, Cox 52’, 56’)
Attendance: 3,362 (125 visiting supporters)