Alessio Bugno equalised within moments of Dave Renyard giving the hosts the lead in the first half at Gillford Park and United sealed their progression to the second round of the Cumberland Cup with a late goal from Paddy Madden.
Reaction from Eric Kinder to follow.
Celtic - Milburn, Arnison (Wallace 46), Hoolickin, Taylor (Wilson 65), Butler, Henderson, Renyard, Earl (Reed 46), Errington, Boyd, J Smith. Subs - R Smith, Anthony.
United - Collin, Gwinnutt, Bugno (Berwick 75), Potts, Livesey (Lynch 63), Staunch, Symington (Salmon 63), Todd, Beck, Madden, Welsh. Subs - Parker, Minor.