Costa dreaming of firing Spanish to glory against homeland Brazil
Diego Costa, who scored twice in Spain's 3-3 draw with Portugal, has said he would relish the chance to face Brazil, the country of his birth, in the World Cup final.
Costa played twice for Brazil in 2013 before deciding to represent Spain the following year.
"I like to see (Brazil) play because I have lots of friends in the team like Willian, Filipe (Luis), Miranda, people that I love, and I don't want things to go badly for them," he said ahead of tonight's Group B game against Iran in Kazan.
"Also in my home in Lagarto (in Brazil), all my family and friends are pulling for Brazil. A Brazil v Spain final would be beautiful, I would sign for that to happen right now, and I wish I could play a great game and win it."
Costa added that he would not expect a backlash from Brazilians over his decision to play for Spain if his dream final were to happen.
"People in Brazil live football with a lot of passion," he said. "But that issue (of switching allegiances) has already passed and people are already used to it. Besides, Brazilians are good people."
Costa initially struggled to make an impact with Spain, scoring just once in his first 10 appearances and not at all at the 2014 World Cup.
He was not included in Vicente del Bosque's squad for Euro 2016 but returned for the World Cup qualifiers under Julen Lopetegui and scored five goals.
"It was important to start strong and score goals," he said after the game against Portugal.
"A striker lives off goals, and I'm delighted with the two that I scored. But there is still a long way to go and I have to continue improving."
Costa stressed that he would not take his place in the starting XI as guaranteed, with Celta Vigo's Iago Aspas and Valencia striker Rodrigo also in contention.
"It's good that there is competition between us as long as it's a healthy rivalry," he said. "We are all a family here and I get on with them very well. If someone else has to play, I just have to support them and congratulate them because they deserve it.
"I'm not going to put on a bad face if I'm not selected. The coach is the one that selects what is best for the group and the national team is above any player."
Costa said appointment of Fernando Hierro, who replaced the sacked Lopetegui three days before the start of the World Cup, had not changed Spain's style.
"Each coach has its own methods, his way of seeing things, but since I've been in the national team it continues on the same path," he added.
Meanwhile, Spain's players "have no doubts" about David de Gea after his error during their opening World Cup match against Portugal, says Hierro.
The 27-year-old Manchester United goalkeeper was at fault for Cristiano Ronaldo's second goal during Friday's 3-3 draw.
"Goalkeeper is a special position, with a special psychology," said Hierro.
"We have no doubts. Honestly. He doesn't doubt himself either.
Ronaldo scored from all three of Portugal's attempts on target, and De Gea was criticised in the Spanish media.
Hierro, who was appointed on the eve of La Roja's opening game following the sacking of Lopetegui, said he "embraced" De Gea after the game.
Iran vs Spain
Kazan Arena, Today, 7.00 pm