"I did not expect it, I was caught by surprise and whilst it is in place of Diego Costa, I'm very happy to be back," Llorente told reporters at a press conference.
"Now it is very difficult to be here, I have to fight a lot, but the year is long and there is time to prove myself. It is always a joy to return to the national team. I have had a normal period of adaptation at Juventus and now I feel fully adapted.
"What I thought was to try to adapt as quickly as possible knowing that this was normal, that it would be tough, but that with the work that I was doing, in the end things would work out."
Spain will face Equatorial Guinea and South Africa over the next week.