Then the unthinkable began to happen. The squad lost 3-1 to Romania and midfielder Gabriel Gomez got a faxed death threat. The coach contemplated resigning.
But the worst was still to come. Defender Andres Escobar, the even-tempered "Gentleman of the Field," accidentally put the ball in his own net in a loss to the United States, and Colombia was out.
Ten days later, the 27-year-old Escobar was shot dead in a Medellin parking lot. The country was stunned.
"Everyone wanted the crime solved, from the president to the most humble of Colombians," said Jesus Albeiro Yepes, the prosecutor who investigating the killing. "I think people would have lynched the three (suspects in the crime) if they had had the opportunity."
The crime reinforced Colombia's reputation as a nation held hostage by cocaine cartels, where professional soccer was rife with drug money and national stars played in private matches for kingpins including Pablo Escobar, who was slain by police in 1993.
The investigation of Andres Escobar's murder reinforced the perception of impunity.
While triggerman Humberto Munoz was sentenced to 42 years in prison, he refused to implicate his bosses, who were with him at the time. He was out of prison after 11 years.
To this day, Yepes wonders why his superiors shelved the case against Munoz's bosses, brothers Santiago and Pedron Gallon, who authorities suspected of involvement in drug trafficking. Some have suggested a paramilitary leader who employed the brothers bribed authorities. Yepes says he has no information on that theory.
On the day of his death, Andres Escobar had gone out with friends to a disco in Medellin to take his mind off the own-goal.
But in the disco, patrons yelled "own-goal, Andres, own-goal!" Yepes said.
Escobar left, and in a nearby parking he was harassed again.
Yepes said Escobar asked why they were bothering him, and Santiago Gallon told the athlete from his car that "he didn't know who he was messing with."
Munoz, the driver of Gallon's vehicle, got out of vehicle and shot Escobar six times.
The Medellin drug cartel was then in decline, the Cali cartel ascendant. Now, both are history, the era of drug kingpins gone.
Paramilitary groups demobilized a decade ago. And the leftist rebel Revolutionary Armed Forces of Colombia is negotiating peace with the government.
In the current World Cup, Colombians have become enthralled again by their team, which has won all four of its games and reached the quarterfinals for the first time ever. It plays host Brazil on Friday.
"Now we have a different Colombia in terms of the country and the team," Valderrama said.