Spain coach Vicente del Bosque has left out Chelsea striker Diego Costa while including Athletic Bilbao veteran Aritz Aduriz and Barcelona youngster Sergi Roberto in his latest international squad.

The current European champions play friendlies against Italy in Udine on Thursday Mar. 24 and Romania in Cluj on Sunday Mar. 27 in preparation for the summer's Euro 2016 finals in France.

Brazil-born Costa has scored just once in 10 caps since switching allegiance to Spain ahead of the 2014 World Cup, and has also been regularly involved in disciplinary issues at club level -- most recently when being sent off during their FA Cup quarterfinal with Everton at Goodison Park.

Diego Costa has scored just one goal in 10 appearances for the Spanish national team. Clive Rose/Getty Images

On presenting the latest list at the Spanish FA's base at Las Rozas near Madrid, the La Roja coach told a news conference that the decision not to call up Costa this time had been made due to fitness rather than disciplinary reasons.

"[Costa's] physical condition is not perfect, so we did not want to force it," Del Bosque said. "If he was fit he would have been picked.

"The situation the other day was not so serious -- and we are not here to punish. We are concerned about sporting behaviour, of course. Diego has been playing well these months and we are still counting on him.

"There are still two months to go. On the disciplinary side -- we would like of course for everyone to behave well."

Aduriz, 35, won his only cap for Spain back in October 2010, but is by far the highest scoring Spaniard so far in 2015-16, having netted 31 times in 47 games across all competitions for Athletic.

"[Aduriz] is coming in by popular acclaim, but also deserves to be here," Del Bosque said.

Aritz Aduriz is the top goal scoring Spaniard this season, with 31 goals in 47 games for Athletic Bilbao. Juan Manuel Serrano Arce/Getty Images

"He is scoring a lot of goals, a traditional centre-forward that everyone likes. Until now there has not been much talk about him coming with us, but he has been playing well for many years. He deserves it."

And Blaugrana utility player Sergi Roberto, 24, is primarily seen as a midfielder at international level, Del Bosque revealed.

"[Sergi Roberto] has played everywhere -- he is capable of playing in many different positions," he said. "But we see him as a midfielder. That is where he has played for the underage Spain teams.

Sergi Roberto will play as a midfielder for Spain, despite appearing in a number of different positions for Barca. David Ramos/Getty Images

"He has played well in some games at right back for Barca -- they play a very attacking style, and he can fit in anywhere."

Barca captain Andres Iniesta has been excused from the two upcoming friendlies as he is not 100 percent fit.

"I spoke personally with [Iniesta]," he said. "The other day he had a bit of a muscle problem, so we thought it's better for him not to come.

"I don't know if he will play for his club, but he is not at 100 percent so we preferred for him not to come, similar to the situation with Diego."

Atletico Madrid midfielder Saul Niguez and Arsenal right-back Hector Bellerin were in his thoughts, Del Bosque added, but for now would continue with the under-21 set-up.

Hector Bellerin has impressed his national coach, but will remain with the U21 side for their upcoming qualifier. Getty

"We are very impressed with Saul and Hector Bellerin, both with their energy and displays. But they will both stay with the U21s, who have a big qualifier to play against Croatia."

Centre-backs Marc Bartra and Nacho Fernandez have both been included in the senior squad, despite both being fourth choice at best for their clubs Barcelona and Real Madrid.

"They are kids we have a lot of confidence in," Del Bosque said. "They have always done well when they came with us.

"They will be very fresh for the Euros. They are not getting much playing time at Barca or Madrid, but in other clubs for sure they would be playing a lot more."