Steve Kabba got the winner for United just 2 minutes from time. He slotted home the rebound after Horwood's shot had been blocked by Gareth Whalley.
The Latics lined up as follows: Walsh, Wright, McMillan, Edwards, Lee (c), Jarrett, Sulaiman, Whalley, Graham, Johansson, Owens (Waterhouse 83).
Subs not used: Joyce, Salisbury, Traynor, Litchfield.