Sunderland were watched by an astonishing crowd of more than 46,000 as they boosted their chances of escaping from League One at the first attempt.
Aiden McGeady scored the first-half goal that lifted Jack Ross's side within five points of leaders Portsmouth with two games in hand.
They deserved their three points against a stubborn and well-drilled Bradford side in a game that will always be remembered because of the remarkable attendance of 46,039 at the Stadium of Light.
It was beaten by only two Premier League games yesterday and was even more than Tottenham attracted to Wembley for their meeting with Bournemouth.