Diego Costa
Diego Costa wants to replicate his Chelsea success with SpainGetty Images

Chelsea striker Diego Costa is aware that he is yet to show his real worth with the Spain national team but has told his critics that sooner rather than later he will prove his doubters wrong.

Just before his £32m ($48m) move from Atletico Madrid to West London, the 26-year-old star decided to play with Vicente del Bosque's side for the last summer World Cup even though he was born in Brazil.

Having failed to make the impact expected in his few appearances with the national team, some fans and even Spain's vice-captain Sergio Ramos have questioned his commitment and whether his aggressive style fits into La Roja's tiki-taka philosophy.

After missing the two previous national team games against Belarus and Germany in November due to an injury, Costa was looking forward to responding to the critics in the ground in the upcoming games against Ukraine on 27 March and the Netherlands on 31 March.

But the striker will be unable to do it after suffering a recurrence of his hamstring problems during the Chelsea 3-2 victory over Hull on Sunday 22 March.

Costa has expressed his frustration about the situation but hopes to have a chance to silent the doubters in the near future.

"I thought that finally I was going to be able to play [for Spain] fully fit. Always when I had gone with Spain before I had hassles. This time I arrived without any problem. I was eager to prove my my worth [...] but I am injured again," the Spaniard said to Marca.

"My story with the Spanish national team hasn't started yet. I haven't done anything yet. I'm sorry not to be able to contribute what I wanted to. Something always happens to me when Spain matches are coming up. I'm raring to succeed with Spain,"

"Sometimes it bothers me that some question my presence [with Spain]. I chose to play for Spain [rather than Brazil] because I wanted to. I proved that I had the desire to succeed with the national team. The best way to shut their mouths is to play and do the things well. But as [until now] I haven't done it I have to listen and swallow [the criticism]."

Costa insists that he is not bothered by those who find fault with his performances, as he is aware he is yet to prove his worth with Spain, but has a problem with his commitment being questioned.

"One thing is criticised is my performances, which is fair, but they can't criticise my commitment. It's too unfair after what I experienced in Brazil in the selection [the Brazilian hit back at him for choosing Spain]. I'll try to replicate my peak form to succeed with the national team."