Oxford United dropped into the League Two relegation zone after only managing a draw at Wrexham's Racecourse Ground.
Oxford must now beat Leyton Orient on the last day of the season to stand any chance of staying up.
Wrexham took a first-half lead after Oxford keeper Andreas Guatelli made a blunder, dropping the ball at the feet of Matt Cromwell who took advantage.
Oxford levelled when Shaun Pejic impeded Eric Sabin in the box and Tcham N'Toya scored the penalty.
Wrexham were bolstered by news the club could soon come out of administration after the sale of the club was agreed.
Wrexham: Michael Jones, Pejic, Danny Williams, Mike Williams, Roche, Crowell, Ferguson (Done 56), Mark Jones (Bennett 45), Holt, Walters (Lawrence 85), Derbyshire.
Subs Not Used: Ingham, Smith.
Goals: Crowell 28.
Oxford Utd: Guatelli (Tardif 32), Mansell, Dempster, Willmott, Robinson, Quinn, Hargreaves (Smith 45), Burgess, Basham (Sills 62), N'Toya, Sabin.
Subs Not Used: Odubade, Brooks.
Goals: N'Toya 64 pen.
Ref: S Tanner (Somerset).