Lee Johnson felt Sunderland produced one of their best performances this season to beat Ipswich Town
Johnson conceded that his team had not been at their most fluid but said they had progressed as a team with the win.
He said they had to show their character after a fine recent run of results, while also noting that they had come through yet more injury problems to get the win.
Dennis Cirkin has been ruled out until the new year with a hernia problem, leaving Johnson with no senior full backs.
O'Nien stepped back into the role on Saturday, but he continues to have his own issues with a shoulder problem.
“I think it was one of our best performances” Johnson said.
“It wasn’t Ajax or Barcelona in their heyday, but we hassled and harried.
“It wasn’t champagne football, we had to deal with their quality but everybody stayed concentrated.
"We've talked about the winter before with our young players [being a potential .Our centre-halves, Tom Flanagan has played against Italy this week and Callum Doyle has played twice for England.
“I think we healed and progressed as a team today because young players showed their steel.
“The players and staff fully deserve that win and I’ve got immense pride in the group and that includes the fans, because it’s been tough.
“We’ve made it tough but in this division only the toughest survive. At times we needed our goalkeeper, at times we should have delivered better than we did."
Johnson admitted that Ipswich had enjoyed 'control' of the game, but noted that in the second half Thorben Hoffmann had been largely untroubled.
The head coach insisted that Paul Cook's side are viable automatic promotion contenders, underling the importance of Sunderland's win.
It lifted the Black Cats back into the play-off spots, and within striking distance of the top two.
"I thought it was a tough game for both teams.
Ipswich, when their two central midfielders roll out into those pockets they get a lot of control, and they're very good at it.
"But I always felt we could be dangerous when we won the ball back and played a good first pass.
"It probably wasn't good enough, often enough.
“First twenty minutes we were poor, we had a gameplan and we didn't adminster it, but after that I was pretty pleased," he added.
"They had control in the second half, but it's what you do with the ball and we've seen that ourselves this season.
"There's the odd give-away and I think it was a good League One game that we’ve edged based on that counter-attacking ability.
"Ipswich are a very good side, a really good professional organisation who will be right up there.
"To get a win, after the recent run we've had, is really important for us and the project."