By Brian Winter and Marcelo Teixeira
SAO PAULO (Reuters) - Brazilian police and protesters clashed on Thursday prior to the opening game of the World Cup, injuring at least five people, although excitement took hold elsewhere as flag-waving fans flooded into the stadium, bars and street parties.
The tournament has been largely overshadowed so far by construction delays and months of political unrest with many Brazilians furious over $11 billion (6.53 billion pounds) being spent to host the Cup in a country where hospitals and schools are often poor.
Throughout much of Brazil, though, the dour national mood of recent months showed signs of finally turning festive. Thousands of local and foreign fans sang and danced in front of giant TV screens set up downtown ahead of the opener between Brazil and Croatia, which the home team was strongly favored to win.
Fireworks also echoed throughout many cities. Kickoff was set for 5 p.m. local time (2000 GMT).
"It's been all peace and love, the people have been very friendly and we haven't had any problems," said Frederico Ortuyo, an Argentine fan watching the game in downtown Sao Paulo.
Late in the morning, police fired tear gas, rubber bullets and noise bombs to disperse demonstrators who gathered in eastern Sao Paulo, about six miles (10 km) away from the Corinthians arena where the game will take place.
A police spokeswoman said the crowd numbered about 600 at its peak. That was up from previous estimates, though it was still smaller than organizers and some police had expected.
After protesters tried to cut off a main road to the stadium, at least five people including some journalists were injured in clashes, police said. Two people were arrested for vandalism, and one for carrying a Molotov cocktail, police said.
About 1,000 protesters in Rio de Janeiro marched peacefully, though some burned Brazilian flags and carried signs saying "FIFA go home," in a reference to the world soccer body. There were smaller demonstrations in other host cities.
What appeared to be the biggest crowd of the day, though, came as several thousand lined Sao Paulo streets to cheer on the Brazilian team's bus as they headed to the stadium.
In downtown Sao Paulo, crowds of Croatian fans were drinking beer by mid-morning. Streets in the bohemian neighborhood of Sao Paulo were so packed with fans that it was hard to move.
The stakes are high not just on the soccer field. Whether the tournament goes smoothly may also have an effect on President Dilma Rousseff's chances for re-election in October, as well as Brazil's flagging reputation among investors. Rousseff, who will attend the opening game, has dismissed complaints about overspending and delays in preparing stadiums and airports. Asked if the home team would win the opener, as it is expected to do, she smiled and flashed a thumbs-up.
FINGERS CROSSED
More than 1 million people joined in the protests last June, but most recent demonstrators have been much smaller, numbering just a few hundred people. Polls suggest that, despite continued misgivings about the World Cup's organization, many Brazilians will start to enjoy it once the goals start coming.
Brazil's team, led by exciting 22-year-old star striker, Neymar, is widely fancied to win a record sixth World Cup title.
In Salvador, another of the 12 cities that will host games, locals were singing soccer songs and playing drums as others hung yellow and green streamers.
"You can feel the atmosphere building up with fans coming here in good spirits," said Ben, an English fan in the sweltering Amazon city of Manaus.
Yet the list of possible problems is long. In fact, hosting a successful tournament may ultimately prove harder for Brazil than winning it. About a dozen disgruntled airport workers blocked a road outside Rio's international airport on Thursday morning, causing heavy traffic.
Some businesses in Rio, the venue for seven Cup games, including the final, had boarded up windows and doors by late on Wednesday in case protests erupted.
The Sao Paulo stadium itself has been a source of anxiety.
Not only was it delivered six months late at a cost of $525 million, about $150 million over budget, but because of the delays Thursday's game will be the facility's first at full capacity. That's a big no-no in the field of logistics and a violation of FIFA's normal protocol for World Cup games.
A rough tournament would likely cause Rousseff's popularity, already under pressure, to fall further. Any major logistical problems and unrest could also further dent Brazil's reputation among investors, which has suffered since a decade-long economic boom fizzled under Rousseff.
Brazil's performance in hosting the World Cup will also give clues as to how well it will do in two years, when it plays host to the Olympics.
(Additional reporting by Paulo Prada and Rodrigo Viga Gaier in Rio de Janeiro and Fabiola Gomes, Brad Haynes, Caroline Stauffer and Esteban Israel in Sao Paulo, Neil Maidment in Salvador and David Ljunggren; Editing by Kieran Murray)