Julian Alsop's superb second-half strike kept Oxford on top of Division Three after a tense finish at Rochdale.
Top-scorer Steve Basham scored on the turn to give Oxford a first-half lead before Alsop's powerful finish.
Rochdale made the early running, Sean McClair volleyed wide and Andy Woodman saved Andy Bishop's shot.
Oxford were forced to hang on after Gary Jones scored with a crisp drive in the 54th minute.
Rochdale: Edwards, Evans, Burgess, Griffiths, Simpkins, Bertos, McClare, Jones, Doughty, Bishop, Patterson. Subs: Gilks, Grand, McEvilly, Beech, Townson.
Oxford Utd: Woodman, Ashton, Crosby, Robinson, McCarthy, Whitehead, Wanless, Brown, Waterman, Alsop, Basham. Subs: Hackett, Louis, Oldfield, Omoyinmi, Townsley.
Referee: M Cooper (West Midlands)