CURITIBA, Brazil — On his first morning as a prisoner, Luiz Inácio Lula da Silva had a breakfast of bread, butter and coffee.

Later on Sunday, he watched a final soccer championship match between Corinthians, which he roots for, and its archrival, Palmeiras. His team won on penalties.

Mr. da Silva, 72, is no ordinary prisoner: Outside the building where he is confined is a plaque with his name on it, commemorating the opening of the building in 2007, during his presidency of Brazil.

The country, the largest and most populous nation in Latin America, has begun to absorb the reality of the downfall of Mr. da Silva, who surrendered to the police on Saturday night, two days after the country’s top court ruled that his 12-year prison sentence for corruption and money laundering could begin, even as he continues to appeal.