June 10 (Reuters) - The last thing that Brazil need when they try and win a sixth World Cup on home soil next year is for their players to lose their cool at a crucial moment in the tournament.
Brazil should have learned the lesson in 2010 when they imploded in the second half of the quarter-final against the Netherlands after the whole team, including coach Dunga, let their anxiety get the better of them.
Yet, there were worrying signs in Sunday's 3-0 friendly win over France that it has not been heeded.
Central defender David Luiz, a pivotal member and leader of the Brazil team, showed the tempestuous side of his character which he appeared to have largely subdued with Chelsea this season.
Early in the game, he took a wild hack at French striker Karim Benzema's leg in an incident which happened near the halfway line.
Having somehow escaped a booking for that offence, he made sure of a yellow card a few minutes later with another crunching tackle from behind on Dmitri Payet.
Again, there was no danger to the Brazil goal whatsoever when he did it.
If it had been a World Cup match with a stricter referee, Brazil would have been down to 10 men in less than half an hour.
The Chelsea defender also produced France's best scoring opportunity when he diverted Mathieu Balbuena's cross straight towards his goal and was only saved by goalkeeper Julio Cesar, who pulled off a point-blank reflex stop to keep the ball out.
David Luiz has improved enormously this season with Chelsea under the guidance of the now-departed interim manager Rafael Benitez, who appeared to have curbed his wilder excesses.
Apart from a few incidents, including a shocking tackle on Jack Reeves during the 4-0 FA Cup win over lower tier Brentford, he made far more of an impression with his leadership, grit and marauding runs upfield.
"I've always said my shoulders are broad and I can take on that extra responsibility," he told the Guardian in an interview in December.
"I love it. I want it. I prefer to take it on myself to help the other guys, who can then go out and play with their heads clear and calm."
However, the pressure-cooker atmosphere of playing for Brazil in front of a home crowd once again brought the worst out of him against the French.
Brazil coach Luiz Felipe Scolari could lessen the risks by following Benitez and moving David Luiz into a midfield role, but said it is not something he intended to do for the time being.
"In principle, I'm not thinking of starting with David Luiz as a midfielder," he said. "But he has showed that he can play very well in that position and, depending on our results and one or other two details, it could be a useful option."
The World Cup, with a group stage following by a knockout contest, can be a cruel competition where a single slip-up or loss of temper can undo all the previous good work.
That was more or less what happened to Brazil three years ago.
They powered through their group and round of sixteen match and looked in little danger at halftime against the Dutch as they led 1-0 after dominating the game.
But they collapsed after a defensive mix-up allowed the Dutch to equalise and went on to lose 2-1, with midfielder Felipe Melo sent off for petulantly stamping on Arjen Robben.
Melo, who like David Luiz plays with his heart on his sleeve, quickly became the scapegoat in Brazil, where anything but winning the competition is regarded as failure.
After a hostile reception on his return, Melo has not played for his country since. (Editing by John O'Brien)