The protesters' slogan that "There won't be a Cup" has dogged Brazil for the past year, marring preparations for the opening match in Sao Paulo's shiny new -- if chronically delayed and over-budget -- Corinthians Arena at 5:00 pm (2000 GMT) today.
Brazil's ambivalence toward the World Cup was on full display as the country geared up for the game, the sea of green and yellow in some areas contrasting with the clashes between police and protesters in Sao Paulo and fears of more nationwide.
In cities across the country, many morning commuters proudly wore the number 10 jersey of star striker Neymar or decked themselves out in the colors of the flag, whether with green-and-yellow shirts, dresses, skirts or flowers in their hair.
In Rio de Janeiro, there was a festive atmosphere as tourists took in the breathtaking views from Mount Corcovado, where an enormous Brazilian flag adorned the base of the iconic Christ the Redeemer statue.
Football fans from around the world sporting the colors of their teams gathered around the monument, one Argentine proudly flying a flag proclaiming "Yes We Can."
In Sao Paulo, where authorities have declared a holiday, fans began congregating early in the morning outside the hotel where the Brazilian team were staying.
Monica Seixas had gone there to take a picture with her dog, both decked out in green and yellow.
"I love the World Cup. I always follow it and now I'm super excited that it's happening in Brazil," said the 57-year-old engineer outside the Hotel Pullman Ibirapuera in the south of the city, which had a heavy police presence around it.
"We've been here since 8:00 am. My son wouldn't let me sleep. He wanted to come see the 'selecao,' and we're not leaving until we see them," said IT specialist Paulo Loria, 49.