The striker's fitness has been one of the talking points of the season - the problematic hamstrings he had at Atletico Madrid still hampering him - and last month club boss Jose Mourinho said he thought his troubles were coming because of his work with Spain.
When asked if he thought Costa was now fit, he said "but he still has to play for the national team in November!" suggesting more trouble could lie ahead.
But Spain coach Vicente del Bosque has overlooked the 25-year-old for next week's fixtures - news which is sure to please Mourinho.
"Costa has some annoyances," Del Bosque said when announcing his squad through the Spanish national team's official website.
He added, suggesting there were no underlying problems: "He is the first who is willing to be with us.
"Our idea is that all 23 players come to be useful."
Costa's Chelsea team-mate Cesc Fabregas is included in the squad, with Manchester United goalkeeper David de Gea and Arsenal's Santi Cazorla the other English-based players.
Spain face Belarus next Saturday, sitting unusually off the top in qualifying group C after defeat to leaders Slovakia
They then face the side which this summer took their world crown, Germany, in a friendly on Tuesday.
Spain squad: Casillas, De Gea, Casilla, Juanfran, Azpilicueta, Ramos, Pique, Albiol, Bartra, Alba, Bernat, Busquets, Camacho, Koke, Cazorla, Fabregas, Callejon, Nolito, Morata, Alcacer, Pedro, Raul Garcia, Isco.
Source : PA
Source: PA