Northern Ireland's World Cup qualifying campaign lies in tatters despite record goalscorer David Healy securing a last-gasp equaliser against minnows Azerbaijan at Windsor Park, as they struggled to a 1-1 draw.
Rauf Aliyev scored a screamer to give the Group F minnows a fifth-minute lead and Northern Ireland conspired to waste at least half a dozen glorious chances to equalise inside 90 minutes.
Craig Cathcart and Chris Baird spurned four of the best between them and it took Healy's first goal in four years, deep in added time, to avert what would have been an embarrassing defeat.
The result leaves Northern Ireland with three points from four games and all but out of the reckoning, as well as consigning last month's heroic draw in Portugal firmly to the history books.
O'Neill started the evening by opting to leave one of his few established Premier League players on the bench, West Brom's Chris Brunt left out in favour of Shane Ferguson, Dean Shiels and Niall McGinn, the latter looking to build on his goalscoring heroics against Portugal.
Burnley left-back Danny Lafferty also earned a competitive debut after Ryan McGivern failed a fitness test.
The home side began positively and should probably have taken a third-minute lead when McGinn floated over a precise cross for Kyle Lafferty, who somehow headed over from just six yards.
That miss was punished within 90 seconds as Azerbaijan took a surprise lead with their first attack.
Javid Huseynov won the ball in midfield and laid off to Aliyev, who bent in a stunning shot from 30 yards before embarking on ecstatic celebrations.
Azerbaijan looked dangerous on the counter-attack and only a Gareth McAuley block denied Aliyev the chance to try his luck a second time.
Northern Ireland, meanwhile, were enjoying plenty of time on the ball but struggling to make the final pass count.
McGinn worked rookie goalkeeper Salahat Aghayev with a first-time shot from the edge of the area and Shiels played an inviting ball across the face of goal but Azerbaijan survived unscathed on both occasions.
After 26 minutes Steven Davis chipped a fine ball over the back four to give Kyle Lafferty a one-on-one attempt but a loose first touch allowed Aghayev to smother.
Another gilt-edged chance came and went on the half-hour, Shiels finding Cathcart with a cushioned header across goal and the Blackpool defender nodding wide from a wonderful position.
Roy Carroll faced a hairy moment when Vugar Nadirov's deflected shot briefly appeared to be heading for the top corner, but the veteran goalkeeper just got back.
There was enough time for one more chance before half-time, Danny Lafferty heading over after getting on the end of Ferguson's hanging cross.
O'Neill resisted the temptation to send on Brunt during the break and the equaliser almost arrived just two minutes into the second period.
McAuley nodded down Davis' free-kick and Cathcart controlled the ball on his chest before blazing over from the six-yard line.
Chances continued to flow, McGinn and Baird the latest to go close, but Kyle Lafferty was booked for a blatant dive after 56 minutes, earning a one-match ban in the process.
If not for Carroll things would quickly have gone from bad to worse.
He raced from his area and produced two sliding tackles to scramble the ball clear when a breakaway goal seemed certain.
On the hour mark Baird produced arguably the worst miss yet, heading Ferguson's cross wide at the far post when scoring seemed easier.
Nine minutes later he spurned another glorious chance when heading substitute Paddy McCourt's cross wide from an unmarked position.
McCourt's jinking runs visibly lifted the home side and Brunt followed him off the bench with 24 minutes to go.
McCourt beat two men as the cut into the box from the left and refused to go down despite a wild challenge.
By now the hosts' frustrations were apparent after every unsuccessful move and O'Neill played his final card by sending on Healy for Cathcart.
It looked like even that would not be enough but five minutes into a generous period of injury time, the fan favourite drilled home a free-kick to rescue a dramatic point.
That is unlikely to be enough to rescue Northern Ireland's slim qualifying hopes but it did save his side from one of their most ignominious defeats.