It was a nervous, tense and fraught 20 minutes, but one that ultimately spoke volumes for the environment Jack Ross is building.
When Max Power saw red for a reckless kick, it looked as if Sunderland were set to slip up again.
In previous years, no one would doubt that they would have gone under.
What followed, however, was an uplifting display not just of spirit and resilience, but of game management and defensive quality.
For a team seeking to establish its promotion credentials, there were an awful lot of boxes ticked.
First there was an outstanding save from Jon McLaughlin.
The summer signing had looked steady in the opening weeks of the season but now he is emerging as something else entirely. Commanding, with excellent distribution and outstanding shot-stopping skills.
A free transfer? What an outrageous piece of business. In the Championship Sunderland faced, and had, far inferior goalkeepers most weekends.
His save, however, only spared Sunderland because it was followed up by a brilliant challenge from Tom Flanagan.
Though Flanagan and Jack Baldwin can both make errors, they defend with so much commitment and the latter again oozed class.
After that, it was testament to Sunderland’s defensive efforts that McLaughlin was not needed to make another significant save.
Jack Ross showed good clarity of thought to make three substitutions that shut the game down.
Chris Maguire moved up front and did superbly, killing time, buying fouls.
He was well supported by George Honeyman who covered acres of ground; Dylan McGeouch offering some welcome composure on the ball just behind.
The most important substitution was that of Alim Ozturk.
The centre-back has had his critics but Ross has insisted that he will need his full squad if Sunderland are to succeed this season.
With Bradford invariably going aerial in their search for an equaliser, Ross rightly decided that Ozturk could add something to his defence.
He did his job well, as he did when last called upon from the bench at AFC Wimbledon.
Reece James, who not so long ago had slipped to third choice, defended steadily and coped well in the early stages when his flank was clearly being targeted by the hosts.
It was a win of collective endeavour and the emotional scenes at the end, on the pitch and in the stands, said so much about how far this club has travelled.
Of course this nervy end should never have happened.
Sunderland looked in complete control in the first half, occasionally playing some good football and looking levels above their opponents.
As on Tuesday, however, they were not ruthless enough and another lapse in discipline left them facing the prospect of dropping more points that should have been wrapped up long before.
There remains a nagging suspicion that the Black Cats are too easily being suckered into niggling scraps by teams whose quality in open play is far inferior.
To seal automatic promotion, that needs to change quickly.
But just as not long ago it was fair to point out that Sunderland had worrying only one won from five, it is worth noting now that since falling to their first defeat of the season, the Black Cats have eight points from four.
That is promotion pace and in that time they have shown resilience and quality.
They can play better, be more efficient and more ruthless. Certainly more disciplined.
But that 20 minutes showed they have the character of a winning side. This is a club developing a powerful unity.