Answer:
I remember the time when Zinedine Zidane, the well-known french soccer player, who is one of the most successful and skilled players in soccer history, attacked the Italian player Materazzi, that event cost the cup to Zidane, because it was during a Worlds Cup. According to some sources, Materazzi insulted Zidane, which triggered his behaviour.
Other opinions say that due to the level of competition, the event, the pressure and intensity of the game, all those factor influenced Zidane to act like that, which was a poor sport behaviour.
I really believe that the context was the main factor that pushed Zidane to act like that, because it was a Wold Cup, the most important tournament in soccer.