The World Cup can be a cruel thing. No matter how well the team is doing in the competition, it need not take a bad game, or even a bad half, for them to be eliminated. A bad few minutes can be enough - as Brazil know very well.
Brazil's team in the last World Cup in South Africa may not have been to everyone's taste, but results were excellent in the two years leading up to the tournament, and at half-time in the quarter-final against Netherlands few would have bet against them. Yet, in a matter of minutes, a 1-0 lead evaporated into a 2-1 deficit, and they were back on the plane home.
Still, that was nowhere near as traumatic as 1950, when the side hosting the World Cup for the first time came so close to winning it for the first time. To clinch the title in front of their own fans in Rio's newly built Maracana stadium, Brazil needed a draw in the final game against Uruguay.
For the only time in the competition's history, the last four teams went into a mini-league. Brazil's flamboyant side beat Sweden 7-1 and Spain 6-1. As coach Flavio Costa explained to me nearly half a century later: "There was nothing for me to do apart from pat the players on the back." His side took the lead against Uruguay, but then disaster struck. As Costa recalled: "Uruguay found a hole in our defence." Right winger Alcides Ghiggia ran riot, setting up the equaliser and scoring the winner. Costa stood helpless on the sidelines.
The Brazil coach in 2014 will be able to do more to change matters. There were no substitutions in 1950 and, had Costa been able to make changes, he would have added extra defensive cover on his left flank. But the man in charge in two years' time will have to put up with pressures that were unknown to Costa - the 24/7 modern media, for example, and the fact that 200 million Brazilians will be demanding success (four times as many as there were the first time the World Cup came to town). He will also have to put up with the ghosts of 1950, the deep psychological fears that lightning will strike twice.
It is a job likely to add years to a man's appearance. Current Brazil coach Mano Menezes is a figure of legendary calm, but the tension showed on Tuesday when he celebrated the last-minute own goal that gave his team a 2-1 win in a friendly against Bosnia & Herzegovina. He knows that the Brazil coach is forever sitting in a coconut shy, with objects hurled at him from all sides. Winning games - even low profile friendlies - is the best shield he can have.
Despite the win, a trip to the cardiologist might still be in order. And one of the motives would be the performance of his unconventional centre-back, Chelsea's David Luiz.
Alongside the imperious Thiago Silva of Milan, David Luiz brings some interesting virtues. He carries the ball out of defence well, and is willing and able to keep driving forward and make a contribution in the last third of the field - very useful against the cautious opponents Brazil are likely to face in 2014, in the early stages of the competition at least.
The problem is the defensive side of his duties. As Chelsea have been discovering, for all his talent, David Luiz is not a natural defender. His display against Bosnia & Herzegovina was deeply worrying. A large parcel of blame for the goal Brazil conceded has to go his way (shared with goalkeeper Julio Cesar - more of him later).
The danger began with his slack pass out of defence, and the problem was compounded when Ibisevic ran at him with the ball. At times David Luiz can be too reckless with his tackles, diving in when he would be better advised to hold his position. Perhaps in trying to avoid this error he went too far the other way, backing off so far until he offered his opponent a free shot at goal.
This was by no means his only mistake. There were other times when he was caught out of position or unsure of what he was doing. Bosnia & Herzegovina's star man Dzeko had by far the best of the duel, turning past him a couple of times with good use of the body, and cutting inside him at will.
Menezes was alarmed, and revealed in the post-match press conference that he had talked to his defender about these mistakes. "Today David Luiz was below the level of David Luiz," he said. But is that really true? Is it not more accurate to argue that the defensive deficiencies of the Chelsea man are being exposed on a regular basis?
Certainly Menezes thought it appropriate to drop Luiz from the team a year ago after a similarly unconvincing display against Karim Benzema and France. The veteran Lucio was recalled as a short-term solution. Next time round, it will be very hard to ignore the claims of Vasco da Gama's Dede. The doubts must surely be building inside the mind of Brazil's coach. Come the hour of truth in 2014, can he really trust Luiz?
He must also be having some doubts about his goalkeeper. True, Luiz backed off so far that he was given insufficient protection, but Julio Cesar is well aware that he should have saved the shot from Ibisevic. It was another error from the Inter Milan 'keeper - a similar one cost a goal against Ecuador in last year's Copa America.
For years, Julio Cesar cultivated an air of invincibility. Time and time again he came to Brazil's rescue. I well recall the 1-1 draw away to Ecuador in the last set of World Cup qualifiers, when Brazil were over-run in the high altitude of Quito. Or the 4-0 win away to Uruguay in the same campaign - the first time Brazil had ever beaten the Sky Blues in a fully competitive game in Montevideo. Had the two goalkeepers been swapped round, it is entirely possible that Uruguay might have won.
But that bubble of invincibility seems to have been pricked when he came unwisely off his line and allowed Netherlands to equalise in that fatal 2010 World Cup quarter-final. That confidence - so vital to a keeper - that resounding belief in his own ability and decision-making has not been seen since. Is this just a passing phase, or is he damaged goods for 2014?
Menezes needs to know the answer. There are few positions on earth as high pressure as that of Brazil's goalkeeper in a World Cup. There is usually little to do, little opportunity to get a feel for the game, but there are times when a little piece of work - a split-second decision - can be of immense importance in the lives of hundreds of millions. Barbosa, the 1950 'keeper, was never allowed to forget that he let in Uruguay's vital goal at his near post - and his failure merely piles yet more pressure on the man who will defend Brazil's goal in 2014. The 'keeper will have to show extraordinary mental strength.
But then so will the whole team - and here Menezes may have other worries. He appears to have settled on Marcelo of Real Madrid as his left back, and was rewarded on Tuesday with a superbly struck goal.
But Marcelo's talent comes with a short fuse. He managed to get sent off twice during the course of the 2005 Under-17 World Cup, and the years have not brought as much tranquillity as his admirers had hoped. There is always the potential for an explosion. Last November, on his recall, Menezes was prowling the touchline trying to calm down his left back in a friendly against Mexico. On Tuesday, there was a moment when he petulantly threw the ball down in disagreement with a refereeing decision. If this is his reaction when the stakes are low, how will he behave in the pressure cooker of 2014?
A single lapse of concentration, a second's lost control, might be all it takes to end the 2014 dream. That is the cruel reality of the World Cup, and Brazil need to select and prepare their squad with that in mind.