It was supposed to be a mini-coronation for Arsenal, a Sunday afternoon stroll around Wembley Stadium before picking up the long-awaited trophy that would surely lead to bigger and better things.
Yet instead of the validation that Arsene Wenger expected and the chance to get his hands on a gleaming silver pot after five long years, the Carling Cup final brought only abject disappointment and a whole bunch of extra scrutiny.
Birmingham City's 2-1 victory was a spectacular shock but was fully deserved. It showed precisely what is possible when fear is left in the locker room, and gave the underdog Midlands club its first major trophy since 1963.
While Birmingham was understandably jubilant, for Arsenal there was only an all-encompassing cloud of dejection and head-scratching and second-guessing.
Most galling of all for the Gunners was that the soul searching could only realistically point in one direction: the boss. Wenger has always done things his own way, but Sunday's match strongly suggests that it was the critics – and not the mercurial Frenchman – who were right.
No one questions Wenger's twin policies of investing in youth and promoting attractive, free-flowing soccer. His efforts in that regard have built Arsenal both a footballing and a financial future that is rosy.
However, Wenger's one almighty folly is one of neglect. Having built a stylish and prodigiously talented squad he has failed to dot I's, cross T's and fill the most obvious of holes.
On such fine details finals are decided, and that was the case here.
Birmingham's Obafemi Martins will go down as the winning scorer in the 2011 Carling Cup final with the decisive goal in the 89th minute. Yet it was a horrendous mix-up between rookie Arsenal goalkeeper Wojciech Szczesny and defender Laurent Koscielny that set it all up, and left Martins with an opportunity he simply could not miss.
Szczesny is a really good young keeper with a bright future, but perhaps the Carling Cup final was not the stage for him, not yet anyways. Wenger, though, has repeatedly allowed the position of goalkeeper thwart him and his team, and not since Jens Lehmann's departure has the side possessed someone who filled anyone with confidence.
The mistake involving him and Koscielny was not entirely Szczesny's fault, yet it is hard to imagine there would have been that kind of panic in a crucial area had Wenger had someone like Manchester United's Edwin Van Der Sar in between the posts.
Time and again, Wenger has refused to splash the cash, most recently when he missed out on Mark Schwarzer at the beginning of this season.
Sunday's setback was galling and even though the Carling Cup is not the most glamorous or important prize on the English soccer calendar, Arsenal's long absence from the winners' circle meant that this would have a very nice addition to the trophy cabinet.
Overconfidence, such a dangerous beast especially in Cup competitions, seemed to beset Arsenal for much of the week. The sense around them was one of expectation of victory. That in itself is no bad thing, as long as it is accompanied by the willingness to fight to the death if necessary.
But even while watching the Arsenal players enter the stadium, there was no sense that this was a special occasion for them, rather it seemed more a formality. They walked off the team bus in tracksuits instead of the traditional Cup final suits and there was no fire in the belly at the outset.
It was Birmingham that had the drive and the spark, and after 28 minutes, it also had the lead. Arsenal never felt comfortable against 6-foot-8 striker Nikola Zigic, and it was the Serbian who headed home and made the upset a real possibility.
Arsenal would pull back the advantage thanks to Robin Van Persie late in the first half, but could not dull Birmingham's swagger. Alex McLeish's side never let their heads drop, never bowed to reputation and inevitability.
"We had to go out there and compete with Arsenal and believe in ourselves," said defender Roger Johnson. "We had to believe we were capable of matching them and we did that."
Arsenal's response to this bitter blow will be critical, and it will tell us a lot about the mettle of this talented yet still unproven squad Wenger has assembled.
The Gunners are not yet out of the English Premier League title race and hold a narrow advantage over Barcelona going into the second leg of their Champions League round-of-16 clash.
The knife edge is right here. This season is not over for Arsenal and there is still some serious potential upside. A couple of defeats, though, and it all effectively could be done – and another fruitless season would be in the books.