It emerged this week that a group of Black Cats stars had shelved a planned trip to Cheltenham Festival amid a run of six league games without a win which has seen the club slide ever closer to the relegation zone.
Reports suggested O'Neill had pulled the plug on the horse-racing jaunt, but sources on Wearside insisted the decision had come from senior members of the squad.
But whoever was responsible, the manager insisted it was the correct course of action ahead of Sunday's crucial clash with Norwich.
O'Neill said: "Initially, they had asked for it, as they had done for the last number of years, and it's fine.
"But when you are looking at some results, enjoyment can come later. Let's go and win some matches first, that would be the most important issue.
"The players do understand - I think they have always done that. Since I have come into the football club, they felt the same a while back.
"We need to win some matches - it's vitally important that we do. We have still a number in which to do so and we have got points to play for.
"My own view is that it was the proper thing to do."
Sunderland's last six league games have yielded just two points and, with QPR and Aston Villa in particular making big pushes, the relative comfort in which they were able to go about their business just a few short weeks ago is close to evaporating.
They remain six points clear of the bottom three but with only 30 points banked from their 29 games to date, there is still work to be done.
Victory over O'Neill's former club - he had two spells there as a player and briefly managed the Canaries - would take them level with Chris Hughton's men and neighbours Newcastle, whose manager Alan Pardew suggested after last weekend's win over Stoke that 33 points at that stage of the season meant safety was all but assured.
The Ulsterman, while accepting Pardew's point, knows that even a win on Sunday would not be the end of the story.
He said: "Well, I wouldn't go along with that. The Newcastle manager has, in the January window, added a lot of strength to his side when it looked as if they might have had a struggle on their hands.
"With the players they have brought in, what they have done in the January transfer window has given them that extra boost for him to make those comments.
"That's entirely up to him. Personally speaking, we need more points on the board than that, that's my view.
"I don't think for one minute he was suggesting that 33 points is enough. What he was suggesting was, I think, that if you get there now at this stage, you are easing your way through the troubled period.
"I was asked a question there, 'Have you ever felt that some side will drop down into it?'. I have never felt that we have ever been out of it.
"It's been tough all season, so from that viewpoint, until we get the points on the board, you are still looking over your shoulder."
O'Neill will hope to have full-back Danny Rose available after he reported a tightness in his hamstring following his return as a substitute last weekend, but James McClean remains a doubt through illness.