SAO PAULO, Brazil — The world has never seen so much yellow, nor so much exuberance for a sport, as it witnessed Thursday as the 2014 World Cup, billed here as the Copa Das Copas, the Cup of All Cups, kicked off in this soccer-obsessed nation.

The party got going with a 3-1 Brazil win over Croatia that was closer than the score indicates. It included an own-goal by Brazil, first in that team’s World Cup history, and a controversial Croatian foul that led to a penalty kick by tournament poster boy Neymar, who scored Brazil’s first two goals.

Croatian coach Niko Kovac was livid after the match.

“That is shameful, this is not a World Cup referee,” he said of referee Yuichi Nishimura. “He had one kind of criteria for them and another for us. There wasn’t any respect for Croatia. If that’s how we start the World Cup, then we may as well give up and go home now.”

Brazil coach Luiz Felipe Scolari saw it differently.

“Millions didn’t see a penalty? Well, the referee did,” he said. “I watched it 10 times. For me, it was a penalty.”

After seven years of bickering, social unrest (including some just before kickoff) and criticism for shoddy infrastructure, the 32-team monthlong tournament finally got under way amid a sea of proud fans in their team’s trademark yellow shirts. Think of all things yellow -—bananas, lemons, Pac-Man, daffodils, canaries, Big Bird — and none is as yellow as the 61,000 fans that rocked Arena de Sao Paulo, packed trains and filled the parks in the city center on a gloriously sunny afternoon.

on a gloriously sunny afternoon.

The tournament’s $11.5 billion price tag has been a source of discontent for many Brazilians, who feel the money would have been better spent on hospitals, schools, health care and the poverty-stricken favela neighborhoods.

A few hundred demonstrators gathered along a main highway leading to the stadium and tried to block traffic Thursday morning. Police pushed them back, fired canisters of tear gas and launched stun grenades. Just after the match started, about 300 protesters marched along Rio’s Copacabana beach and protested outside the FIFA Fan Fest, a gathering spot where thousands of fans gathered to watch the match on jumbo screens.

The first goal of the match was a shocking 11th minute own-goal by Brazil defender Marcelo. Ivica Olic’s low cross deflected off Nikica Jelavic and into the path of Marcelo, who stuck out his leg to clear it and inadvertently knocked it in, causing a hush in the stadium. No host team has ever lost its opener, and Brazil didn’t want to be the first.

Neymar restored Brazilian pride and tied the game with a 29th-minute left-footed goal off a nice feed from Oscar, who battled in the midfield to win the ball. The stadium erupted as Neymar’s shot careened off the right post into the net. Brazil coach Luiz Felipe Scolari roared, and fireworks exploded all over town.

Then, in the 69th minute, came a game-changing moment Croatians won’t soon forget. Brazil forward Fred went down in the box after slight pressure from Dejan Lovren, and referee Yuichi Nishimura booked Lovren with a yellow card and gave a penalty kick to Brazil. Neymar stepped up, the pressure of the nation on his slender shoulders, stutter-stepped and then launched his shot.

Croatian keeper Stipe Pletikosa guessed right, and got both hands on the ball, but it went in anyway, delighting the home crowd.

Kovac did not mince words after the match.

“The rules were not the same for us and them,” he said. “If that’s a penalty, then we can just stop playing football right now. Let’s play basketball instead.”