Julen Lopetegui is adamant that his World Cup squad will be made up of the most in-form players available to him when the time comes to name it, meaning that a number of top players could miss out on a place.
According to Spanish publication 'AS', Lopetegui's options are currently split into three groups of hopefuls.
The first group, including the likes of: David De Gea, Sergio Busquets, David Silva, Sergio Ramos, Gerard Pique, Koke, Jordi Alba, Dani Carvajal and Andres Iniesta are undisputed selections, players who will all be on the plane, fitness permitting of course.
Then, there is the second group, with the likes of: Nacho, Cesar Azpilicueta, Saul Ñiguez, Asier Illaramendi, Sergi Roberto, Alvaro Odriozola, Iago Aspas and Alvaro Morata, who are all looking odds-on to be included in the 23.
Finally, there are the players who are facing a race against time to prove that they deserve the chance to represent their country at the World Cup.
Athletic Bilbao goalkeeper Kepa Arrizabalaga is the first player at risk of missing out, with his recent injury problems meaning that Villarreal's Sergio Asenjo could leapfrog the Basque in the pecking order as the 'Yellow Submarine' continue to challenge for the Champions League places.
Next, there is Bayern Munich playmaker Thiago Alcantara, who is enduring yet another injury-hit campaign in Bavaria.
Finally, Atletico Madrid winger Vitolo and Real Madrid playmaker Marco Asensio both need to secure more regular playing time should they hope to force their way into the reckoning.
There is one exception to Lopetegui's rule though in the form of Isco. The former Malaga man has been benched following the return to fitness of the 'BBC', but the Spain boss is a huge admirer of the player and his silky skills, meaning that he will be included in Spain's squad regardless of his involvement in the Spanish capital.
There are still over 100 days to go until the start of the World Cup but in many ways, the countdown has already started as Spain look to reclaim their title as the world's best.