The upbeat mood didn't last long. Even before he had played his first match, he was the subject of a racist attack, the kind that has become common for black soccer players across Europe.
Mexico has a history of racism on the pitch. But it was largely overlooked until the arrival of Ronaldinho. Racism in Europe often involves white against black.
But in Mexico and other parts of Latin America that have mixed-race societies, it can involve dark-skinned people shouting insults at other dark-skinned people.
"Seriously, I try to be tolerant, but I hate football and the idiotic phenomenon it produces," Trevino wrote. "I hate it even more because people flood the streets, meaning it took me forever to get home. And all this to see an ape; a Brazilian, but an ape just the same."
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Following a wave of criticism, Trevino apologized to the club and player. But he received no punishment, which typifies how Mexican football officials have dealt with the growing problem.
"Mexico is not a racist country," he said. "This is a country where we use nicknames. On the streets, they single people out. There are profanities that, when they are said, do not mean what they literally mean. Calling someone by a nickname is not discrimination. Those who cross the line should be taken to court," said de Maria.
Valeria Berumen, a high-ranking official of a Mexican government office that works to combat racism, says,"There are two engines that push discrimination. One is football. The other is the Internet. They have the ability to spread positive messages, but they also can spread discrimination, racism and xenophobia.