The 60-year-old arrived on Wearside to overwhelming popular acclaim 12 months ago, sparking a revival which hauled the Black Cats away from the Barclays Premier League relegation zone and to safety long before even he had expected to accomplish the first phase of his mission.
A year on, O'Neill's men find themselves in the bottom three as a result of claiming only two victories in their last 23 league games, and he heads into tomorrow night's re-arranged clash with fellow strugglers Reading with former England and Newcastle skipper Alan Shearer having used his newspaper column to suggest anything but three points could prove fatal for the Ulsterman.
However, the former Aston Villa manager continues to enjoy the support of owner and chairman Ellis Short and remains confident he can turn things around at the Stadium of Light.
O'Neill said: "So what do you do then? So you go and put someone else in charge, he gets a group of 12, 13 games and can't win any matches? It's the same thing.
"I don't want to sound wildly boastful, but not only am I the best man for the job, I am actually the only man for the job.
"We will steer it through, we will get calmer waters ahead - it might take us a few months to do that - and then we will see.
"If we are continuing for the next couple of years to be in this position, then I will certainly question it then."
Despite the disappointing sequence of results, the red and white faithful have not yet turned on O'Neill, the manager whose appointment they had craved for years before Steve Bruce's departure made it possible.
Indeed, they applauded his players off the pitch at the end of Saturday's 3-1 home defeat by Chelsea after seeing them launch a spirited, if ultimately fruitless, fightback.
O'Neill was allowed to invest heavily in Scotland striker Steven Fletcher and England winger Adam Johnson during the summer with Short forking out £22million in transfer fees alone for the pair.
But while Fletcher hit the ground running - he had scored six goals for the campaign before an ankle injury ruled him out of the Chelsea game - Johnson has taken time to settle in, although his goal against the Blues capped one of his more encouraging displays to date.
Nevertheless, Sunderland have won only two league games all season, and just one on their own pitch, and the manager knows until performances start to yield points, it is difficult to claim progress has been made.
He said: "Progress eventually, no matter what you think about it, is determined by results on the pitch, and we are in a similar position, so you could say whether we have made that sort of progress or not.
"It's interesting because it's really the same squad that we have had - we still have, I think, about 19 players from last season.
"The spirit is still there, and that was the thing I noticed most, really, that it hadn't been broken, and that spirit should stand us in really decent stead.
"But spirit alone is eventually not enough. Of course you need to add and we need to get stronger if we can."
Fletcher is making progress, but is unlikely to be involved tomorrow night, and that could mean another opportunity for teenage striker Connor Wickham, who replaced him at Norwich and deputised at the weekend.