Spain striker Diego Costa does not expect to face the wrath of his home nation at the World Cup, despite having turned his back on playing for Brazil.

"So far it has been fine and people have treated me how I expected, although it may not always be like that," Costa told a news conference at Spain's World Cup base in Curitiba on Tuesday.

"I feel relaxed as I have the support of a lot of people who understand what the situation is."

Brazilian-born Costa has chosen to represent Spain, where he plays his club football with Atletico Madrid and made his debut for Spain in a friendly against Italy last March.

He was a revelation in La Liga last season, scoring 36 goals as Atletico won the title and reached the Champions League final.

Costa is from Lagarto in the north east of Brazil, and there is overwhelming support for him in his hometown, with plenty of Spain flags and shirts on display.

"We are a small corner of Spain in Brazil, and they have won 100,000 Brazil fans," his brother Jair said.

"They treat me in a special way, and I feel very comfortable there. It has been incredible" - Diego Costa on his welcome into the Spain squad.

Costa's family will travel the 350 kilometres to Salvador de Bahia to watch Spain's opening game on 13 June against the Netherlands.

"My parents are very happy because now I am closer to them. They have always supported the decision," Costa said.

Costa is a rival player who opposition fans have come to hate for his combative, but away from the pitch he has a likeable charm and has been warmly welcomed by his Spain team-mates.

"They treat me in a special way, and I feel very comfortable there. It has been incredible. I am going through a great period at the moment, and I have to be grateful for it," he said.

Costa came through a fitness test against El Salvador last weekend, having suffered recurring hamstring problems in the latter stages of the season.

He played most of the friendly and suffered no ill-effects.

"I needed that game to get rid of the fear that I might suffer another injury. The last two times I felt fine, then played and had a repeat of the injury. Now though I feel a lot better," said Costa.

"It is normal to be anxious before the start. We face a very strong team and we are all training each day to be at our best."