Bradford City 0-1 Peterborough United
Kyle Vassell's second-half goal ended Bradford City's unbeaten start.
The home side began the brighter, but Conor Washington and Ricardo Santos both missed good chances for the visitors in the first-half.
Posh then went ahead shortly after the break when Michael Smith teed up Vassell, who fired into the top corner.
James Hanson tried a strike from distance late on, but he could not prevent the Bantams from suffering their first defeat of the campaign.
Peterborough move to second in the table, while Bradford slip to eighth place.