Costa has been in fine form for Chelsea this season with 17 Premier League goals.
The striker was left out of Spain’s squad for Euro 2016 after poor performances for the Blues last season.
Spain boss Julen Lopetegui has praised Chelsea star Diego Cotsa
But he has admitted this week he is now enjoying life with the national team.
And Lopetegui has now heaped praise on the Chelsea star.
"He's calm and happy," Lopetegui told Radio Marca.
Top five Chelsea players this season
Wed, March 22, 2017
Who are the top five Chelsea players in the Premier League this season, according to WhoScored.com?
1 of 6
Which Chelsea stars have performed best in the Premier League this season?
"He has had a lot of consistency and form at Chelsea and we are all delighted.
Get Quotes on Home Insurance
"The players who are with us have shown incredible behaviour.
“The players are the medicine for the Spain team and they will help us achieve our goals."