BRASILIA (Reuters) - Neymar's stunning early strike set Brazil on the way to a 3-0 win over Japan in the opening match of the Confederations Cup on Saturday although the occasion was marred by trouble at a protest outside the stadium.
More than 30 people were injured and 22 arrested as police used rubber bullets and tear gas to disperse protestors angry at the amount of public money being spent on stadiums for the tournament and next year's World Cup.
President Dilma Rousseff and FIFA president Sepp Blatter were jeered before the match at the Mane Garrincha National stadium as the public showed their discontent.
Some fans in the 67,000 crowd had to be treated for the effects of tear gas fired by riot police at about 500 protesters outside the rebuilt stadium, which like many other venues has been plagued by delays.
On the field, it was plain sailing for five-times world champions Brazil as second-half goals from Paulinho and substitute Jo completed a comfortable win in Group A of the eight-team tournament.
Boosted by Neymar's early strike, Brazil, playing their first competitive match since the Copa America nearly two years ago, dealt competently with the Asian champions who created some nice moves in midfield but lacked punch.
"What mattered most was the result and this continued the tactical evolution of the team," said Brazil coach Luiz Felipe Scolari, whose side beat France 3-0 in a friendly last Sunday.
"I thought Neymar played very well, he ended a run without scoring, and I only took him off as he had a slight injury, added Scolari. "I've no idea what happened outside the stadium, I have to focus on my team and I can't comment on that."
The game, featuring the only two countries already sure of a place in next year's World Cup, came alive after three minutes when Neymar smashed home a right-foot shot from the edge of the area after a long cross from Marcelo was chested down by Fred.
That lifted the spritis of the fickle yellow-shirted home fans but they began to show their impatience soon enough as Brazil failed to build on the early goal and Japan came into the match with Keisuke Honda making inroads in midfield.
Japan, who started with only Shinji Okazaki as the nominal front man, began to look increasingly dangerous with some incisive moves through the middle but they never seriously troubled goalkeeper Julio Cesar.
Japan's Italian coach Alberto Zaccheroni was surprised at the way his team performed, saying: "Normally we play with a different approach and we make fewer mistakes and take the imitative much more and this did not happen today".
"Either we were so shocked by going one down so early that this worried us and we did not play our normal game, or we were tired following our recent flight back from Qatar and we did not have time to regain our full fitness," he added referring to the return from Doha after beating Iraq in a World Cup qualifier.
"Either way, I'm not that upset but I'm disappointed because we can play much better than that. And to be honest, I haven't learnt that much about my team that I didn't know already - the truer test will come in the games against Mexico and Italy."
Despite allowing Japan the room to indulge in some clever passing play, Brazil also showed flashes of flair.
Neymar, who told reporters afterwards he was fit and had only suffered a slight knock, produced a little shimmy on the left, but failed to get past his marker, while Hulk, working up the right wing, fired into the side netting.
Impressive striker Fred forced Eiji Kawashima into a fine one-handed save with a low snapshot after a floated cross from Neymar two minutes before the break.
Three minutes after the interval, Brazil did find the net again when Paulinho met Dani Alves's cross and blasted home.
In a largely uneventful second half, Brazil coped easily with the limited danger Japan created before Jo finished off a counter-attack to wrap up the victory nine minutes after replacing Fred.
The match was the first international to feature goal-line technology although the technology was not called into action.
Reporting by Mike Collett; Editing by Brian Homewood