MADRID, May 27 (Xinhua) -- The Spanish World Cup squad is to begin its preparations for the 2018 World Cup finals on Monday when the players meet at the headquarters of the Spanish Football Federation outside of Madrid.

The 23 players in the squad, minus the five Real Madrid players who played in the Champions League final in Kiev on Saturday, will start work under the guidance of coach Julen Lopetegui.

Lopetegui has called on seven "young promises" to cover for the absence of the Real Madrid players, who will not join up with the squad until June 4 and it is possible that Yeray Alvarez, Unai Nunez or Carlos Soler could make their debut when Spain play a preparation game against Switzerland in the Estadio de la Ceramica in Villarreal on June 3.

One of the first issues he will have to deal with is the hamstring injury suffered by Dani Carvajal during the Champions League final, the Spain coach will have to assess whether Carvajal will be in condition to travel to Russia or if he has to call a replacement, either one of the "promises" or Barcelona's Sergi Roberto.

Two Spanish players, David Silva (Manchester City) and Nacho Monreal (Arsenal) have already begun work at the Federation's training ground, carrying out some training sessions with third tier side Navalcarnero, to ensure they remain in shape, as the English Premier League ended a week ahead of that in Spain.

The Spanish will fly to Russia on June 7 and will play another preparation game, this time with the full squad available, against Tunisia in Krasnodar on June 9, just six days before they kick off their World Cup campaign against Portugal in the Fisht Stadium in Sochi.

The Spanish will see the Portugal game as the key to qualifying for the last 16 from a group also containing Iran and Morocco and they will hope to have assured their place in the next round after their game against Iran in Kazan on June 20.

Morocco will be Spain's last rivals in the group stage and Lopetegui will no doubt warn against complacency against a tough rival full of players with a wealth of experience in European leagues.

The coach is leading Spain in his first major tournament, but will travel in confident frame of mind after an unbeaten qualifying campaign and the decision taken by new Federation President, Luis Rubiales last week to extend his contract until the end of the 2020 European Championships no matter what happens in Russia.

Spain won the 2010 World Cup, but crashed out of the group stage in 2014. Now with a squad consisting of veterans such as Gerard Pique, Sergio Ramos and Sergio Busquets and youngsters Marcos Asensio, Alvaro Odriozola and Kepa Arrizabalaga, Spain will look to go a long way on the road to Moscow.