Over 30 players are almost certain to be travelling to Russia with their national teams, with some others also likely to join them such as Sergi Roberto, who is one of several tough decisions for Spain coach Julen Lopetegui, with El Clasico a great opportunity to make his case.
For now, there are 32 World Cup players who will take part in the Clasico, with 17 from Barcelona from 10 countries (Spain, France, Portugal, Germany, Croatia, Brazil, Argentina, Uruguay, Colombia and Belgium).
For Real Madrid, there will be 15 representatives from eight countries (Spain, France, Portugal, Germany, Croatia, Brazil, Costa Rica and Morocco).
It would be highly unlikely that neither team will be represented by the eventual winners of the tournament in Moscow on July 15.
Spain will constitute the most heavily represented national team with 10 players, whilst Brazil and France have four each and Croatia boast three.
As is the case each season, El Clasico will capture the attention of fans around the world even if the league title is already secured for the hosts.
Around 500 million people from 192 countries are expected to watch, many in ultra-high-definition thanks to 30 UHD cameras which will allow the game to be seen as never before.
TV companies will also be able to use Laser Wall, the latest technology to show a straight line to clarify offside calls.
Be The Player will also be in use, allowing fans to see exactly what a player sees whilst on the pitch.
There will also be cameras specifically trained in on Cristiano Ronaldo and Lionel Messi in order to show every second of their performances.