The striker believes he will be fit in time for Spain’s opening game and he is determined to repay the faith that coach Del Bosque has shown in him
Diego Costa says he is confident he will have recovered from injury before Spain's first World Cup fixture, against the Netherlands on June 13.
The Atletico Madrid striker struggled with a niggling hamstring injury towards the end of the season and lasted just nine minutes of the Champions League final loss against Real Madrid - but he believes he will be fit in time for the opening Group B clash.
The forward is confident of breaking into coach Vicente Del Bosque's side and his fitness is set to be tested in Spain's friendly against El Salvador in Washington DC on Saturday.
"I think I feel pretty good,” Costa told reporters. “I was recovering for that week after the Champions League final and it's been a while since I've been fully able to recover.
"Now I want to train because I've hardly done anything over the past several weeks. The only thing that matters now is training. Will I be fit in time for the World Cup opener? Of course, why not?"
Costa has admitted that he flirted with the thought of missing out on the Brazil spectacle, admitting his injury could have been even worse than it is.
"Of course the thought that I might miss the World Cup crossed my mind, I was afraid it was something more significant," he said.
"I thank the boss [for calling me up] and I'm going to try and give my all to repay his confidence in me.
"I want to show him that I was worth all the trouble."
Costa has also revealed that he is being held back from participating in competitive action by the national team's medical staff.
"I want to train normally, but they won't let me," he added.
"I have to speak with the doctors, but I think I can play.
"I'm very happy. This is something special for me. I hope I can do as well as I did this season."