(Adds quotes, match details, new reporting from Cuiaba)
By Brad Haynes and Mary Milliken
SAO PAULO/CUIABA, June 13 (Reuters) - World Cup fever intensified across Brazil on Friday as violent protests subsided, fans streamed to a second day of matches and a crushing defeat for defending champions Spain set the tournament alight.
Despite a last minute scramble to get some venues ready and heavy rains in northeastern cities that hosted the day's first two games, dramatic on-the-field action eclipsed most of the concerns outside stadiums.
Raucous fans watched the Netherlands humiliate Spain, the team that beat the Dutch for the title four years ago, with a 5-1 pummeling.
A plucky Mexican team, despite having two goals controversially disallowed, then beat Cameroon 1-0 under a downpour.
After years of construction delays, alleged corruption and sometimes violent protests over the $11 billion spent by Brazil to host the World Cup, the tournament has had a good start.
Brazil won the opening game against Croatia on Thursday and a lack of major problems or street demonstrations on Friday helped organizers breathe easier
Still, security forces remain on the alert after a year of protests contrasting the high cost of the tournament with the poor state of public services and investments in Brazil.
Although demonstrations have progressively grown smaller since mass protests last June, small but more radical groups of activists continue efforts to disrupt the tournament and they have planned marches for the weekend.
Brazil's opening victory unleashed celebrations into early Friday, with fireworks and car horns echoing for hours as fans got into the spirit of the first World Cup on Brazilian soil since 1950.
Shopkeepers in Rio de Janeiro and Belo Horizonte on Friday cleaned up storefronts that they had boarded up for opening day, when some protests broke into scattered clashes with police.
About 100,000 police are patrolling Brazil's 12 host cities during the month-long tournament, complemented by nearly 60,000 soldiers.
After police used teargas, stun grenades and rubber bullets against protesters in some cities on Thursday, especially Sao Paulo, Amnesty International said they deserved a "yellow card."
President Dilma Rousseff, who is running for a second term in October and was loudly jeered at the opening game in Sao Paulo, told supporters from the ruling Workers' Party that the derisive chants "will not intimidate me."
Most soccer fans said they now want to enjoy the Cup even if they agree with the grievances raised by protesters.
"They won't stop us having our fun, especially when Brazil win!" said Pedro Ribeiro, 29, a businessman in Belo Horizonte.
"People have a right to complain. There are lots of problems in Brazil. But they don't have the right to be violent or to spoil the World Cup," he added.
Hours before Friday's games, questions still hung over finishing touches in some host cities.
In the northeastern city of Natal, pouring rain, striking bus drivers and lingering safety questions about the stadium marked the run-up to the Mexico-Cameroon match.
Temporary new bleachers only cleared 90 percent of a safety check on Wednesday, officials told Reuters, and inspectors were barred from entering the stadium on Friday while world soccer body FIFA prepared for the match.
As many as 100 fans were moved to alternative seating due to safety concerns about the new bleachers, a FIFA spokesman said.
Natal also resorted to using school buses and vans to keep public transportation flowing after a bus drivers' union voted to strike over a wage dispute.
Making it more difficult, days of sunshine in Natal gave way to driving rain that flooded city streets and drenched fans in the Dunas arena. The downpour knocked out some of the stadium's security scanners.
Rain in Porto Alegre also interrupted construction around the World Cup arena, which remains a muddy work site just two days before hosting France vs Honduras.
In Cuiaba, a dry heat cooked the dusty roads around the Pantanal arena. Workers were still scrambling on Friday morning to install air conditioning and carpets, just hours ahead of the Chile vs Australia match.
Across the country, however, Brazilians' good cheer was already overwhelming the rocky preparations in the minds of visiting fans.
Just before kickoff of the day's last game, Christian Reilly, an Australian business executive, made light of the fact that much of the infrastructure promised in Cuiaba, including a light rail system and an airport upgrade, is still not finished.
"We were surprised our hotel was there," he joked. "But it's good. We are just having a good time." (Additional reporting by Andrew Cawthorne in Belo Horizonte, Michael Kahn in Natal, Steve Keating in Porto Alegre, Philip O'Connor in Recife, Mary Milliken in Cuiaba and Brian Winter in Sao Paulo; Editing by Paulo Prada and Kieran Murray)