For the second time in a week, Peterborough United were beaten by a promotion-chasing side by a solitary goal and this time it was a strike that will win no awards at the end of the season - Alex Jones credited with the close-range finish midway through the first half.
In a game of few chances, played on a shocking surface, the Bantams only really came under pressure late on when Marcus Maddison fired across the six-yard box, but it was Tom Nichols who probably missed the best opening of the encounter.
The former Exeter City man saw his shot blocked after good work from Craig Mackail-Smith down the right but aside from shots that went over the crossbar, Colin Doyle was not really called upon to make any notable saves.
Maddison saw a free-kick nestle into the side-netting, while Michael Bostwick sent a looping header over the crossbar late on after a corner had caused panic in the Bradford defence.
Substitute Dieng squandered a fine chance to make the game safe late on before four minutes of stoppage time was indicated by the official, who cautioned Andrew Hughes, Anthony Grant, Martin Samuelsen and Tom Nichols during the 90 minutes for various levels of offences.
Posh are now in ninth place in the League One table, eight points adrift of the play-off positions ahead of Saturday's home clash with Oxford United at the ABAX Stadium.
Tickets are available for that match at www.theposhtickets.com, via the Ticketmaster hotline 0844 847 1934* and in person at the ABAX Stadium Box Office.
*calls cost 7ppm plus your network access fee.
Bradford: Doyle, Meredith, Vincelot, Marshall (sub Dieng 79min), Wyke, Cullen, Gillead, Jones (sub Hiwula 65min), Knight-Percival, McArdle, McMahon. Unused subs: Sattelmaier, Toner, Clarke, Penney, Devine.
Posh: McGee, Smith, Hughes, Bostwick, Tafazolli, Grant (sub Inman 60min), Taylor (sub Samuelsen 75min), Maddison, Mackail-Smith, Nichols (sub Morias 76min). Unused subs: Tyler, Binnom-Williams, Da Silva Lopes, Anderson.