The prolific attacker has no regrets over his decision to snub Brazil for the reigning world champion and is eager to prove his worth to la Roja coach Vicente del Bosque.
Atletico Madrid striker Diego Costa feels "privileged" to have been called up for Spain's national side.
The 25-year-old made two appearances for his native Brazil in friendlies last year but pledged his allegiance to la Roja in October and is now set to make his debut for his adopted country against Italy at the Vicente Calderon on Wednesday night.
Much has been made of the forward's decision to snub his homeland and Selecao coach Luiz Felipe Scolari criticized Costa for turning his back on his country of birth, but the 25-year-old is in no doubt that he made the right choice.
"I never imagined that his decision would attract such attention," Costa told Canal+. "When I realized there was interest from Spain I started to imagine things, and thought 'why not?'. It is a privilege that the world champions want you to play for them, especially given the quality of players they have.
"I felt very important. I value it a lot. Vicente del Bosque showed me the person that he is. I like to talk with people face to face, I feel the truth and lies, and Vicente was very clear. He didn't promise me anything. I don't like it when people promise me things, I like to earn it. This, I value."
Costa has scored 27 goals in all competitions for Atletico this season.