Vicente del Bosque named Diego Costa for Spain's matches against Luxembourg and Slovakia.Reuters

Spain boss Vicente del Bosque has sent a new message to Chelsea manager Jose Mourinho, claiming he would keep naming Diego Costa for the National team if the striker keeps playing regularly for Chelsea.

The Chelsea boss has insisted on a number of occasions that the Spaniard is unable to play more than once a week.

However, after Mourinho handed Costa three successive starting appearances against Aston Villa, Sporting Lisbon, and Arsenal, Del Bosque also decided to include him for the Spanish Euro 2016 qualifiers against Slovakia on 9 October and Luxembourg, three days later.

The Premier League top scorer indeed played both games as a starter, scoring his first goal for Spain in the 4-0 victory over Luxembourg.

When questioned during an interview with AS why Costa played two games in a row despite Mourinho's concerns, he said: "I do not want conflict with anyone. We are almost getting onto mystical ground here.

"All I said, and still say, is that Diego Costa, like any other player, will not play if he is not able to. But if he is well, he will play with the national team. The muscle injuries are very difficult to prove," Del Bosque said.

Del Bosque reminded that Costa was withdrawn from the squad during the previous international break, playing in a friendly defeat to France but missing the next game with Macedonia.

"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."

The Spain boss has confirmed he will leave the national team after Euro 2016, having refused to resign before despite heavy criticism.

Meanwhile, when questioned about whether Manchester United keeper David De Gea can replace Iker Casillas as the number one in the coming games, the boss hinted there will be a transition sooner rather than later.

"Transitions can be sweet or traumatic. In the case of the goalkeeper, Casillas is a huge goalkeeper with a fantastic history and for a man with the respect of Casillas, we must combine the present with the future," said del Bosque.

"It is normal for us to worry about the medium term and the other goalkeepers that come such as De Gea or Kiko Casilla. What we want is a normal transition, as there have been before. I remember the cases of Capdevila and Marcos Senna; Senna continued with us for another year while Busquets was integrated.

"That's what we want. But yes, consideration has to be taken with Casillas - we don't know how long he will last. This is not an overnight thing. Maybe up until the 2018 World Cup should be a goal of Iker Casillas, but our next step is to France 2016."