Spain coach Vicente Del Bosque has said Chelsea striker Diego Costa only plays for La Roja when he is fit and claimed that muscle injuries can sometimes have a "mystical" element.
The condition of Costa's hamstring has been debated in recent months, with Blues manager Jose Mourinho suggesting ahead of the most recent Euro 2016 qualifiers that the striker should rest and recover properly.
But the Premier League's current top scorer played in both of Spain's games, finally notching his first international goal in the 4-0 win in Luxembourg.
Media in England and Spain have hinted at a club versus country row between the two former Real Madrid coaches -- but in an interview with AS, Del Bosque said Costa only played for Spain when he was in the right condition to do so.
"I'm always asked about the same things," he said. "[Iker] Casillas, Diego Costa, Mourinho and sometimes Florentino [Perez]. But it does not bother me. I do not want to enter into conflict with anyone.
"The only thing I said, and say now, is that Diego Costa, like any other player, will not play if he is not fit to do so. But if he is in good condition, he will have to play with Spain.
"Muscle injuries are difficult to show. We are almost getting onto mystical ground. This is not so complicated: if he is fit, he plays, like in Paris. If he is not fit, he returns to his club as happened for the Macedonia game."
Brazil-born Costa may not be the last player who is persuaded to switch allegiance to Spain, Del Bosque revealed, saying he was currently considering the situations of Athletic Bilbao's French-born Aymeric Laporte and Granada's Colombian defender Jeison Murillo as he looks to address a centre-back shortage.
The coach, who again stated his intent to retire from the Spain job after Euro 2016, said both players were of interest to him but nothing had yet been decided.
"We will try and take advantage of what we can," he added. "Laporte and Murillo have chances. A friend put us on to it. But that does not mean I am going to call them. It is like [Barcelona's] Munir.
"It was said that I called him up because he was going to be called by Morocco. It was not for that. It was because he had earned it. Because the kid deserved it.
"That is the priority for everyone, also for Laporte and Murillo. We are aware of the rules. They have gone to play, Laporte with the France under-21s and Murillo two friendlies with Colombia. I am aware of both of them. But I will not call them up just because I can."
L'Equipe this week published an interview with Laporte, in which the 20-year-old appeared to say he was becoming fed up with waiting for a call from France senior coach Didier Deschamps.
However, the Agen-born youngster later tweeted a message to say his words had been taken out of context and he "would continue to play with France."
- aYmeric Laporte 4⃣ (@Laporte) October 15, 2014