LIMA, Peru — The thousands of fans arrived at the Estadio Nacional as a sea of red and white.

For more than an hour, they had paraded through the avenues of central Lima, dressed in their national team jerseys, blowing their vuvuzelas and pushing their children ahead of them in strollers. Now, after filing inside Peru’s national stadium, they sang Peru’s national anthem, waved Peru’s flag and hoped — against the longest of odds — that their festive display of national camaraderie would not be in vain.

For a week, their energies, and much of Peru’s attention, has been focused on the case of Paolo Guerrero, the star striker who helped lead his nation to its first World Cup in 36 years but now seems all but certain to miss the tournament because of a doping ban. Commentators, the national team coach and even Peru’s president had taken up Guerrero’s cause.

But on Sunday, it was the fans who wanted to be heard. “Pardon Paolo!” read one handwritten sign. “I want my captain at the World Cup,” said another.