The manager had been expected to cut his 30-man roster to 23 on Sunday but has decided to wait until the June 2 deadline.
Spain coach Vicente del Bosque has postponed the announcement of his final World Cup squad, instead naming an 18-player team for Friday's friendly against Bolivia.
The 63-year-old had been expected to reveal the identity of the 23 players that will be traveling to Brazil but has instead decided to wait until the June 2 deadline before finalizing his selection because of the involvement and Real Madrid and city rival Atletico in Saturday's Champions League final.
Indeed, Del Bosque said that he does not yet know what shape Rojiblancos right back Juanfran and striker Diego Costa are in.
"We've done this because we don't know the physical conditions of all the players," the former Real boss told reporters Sunday. "Until June 2 we are not obliged to announce it to FIFA and we would like for all of them to get here before then and evaluate them in training conditions.
"The World Cup kicks off against the Netherlands and we want all of them to be in top form. Except for Juanfran and Diego Costa, who we don't yet know how they are after the Champions League final, we know the conditions of the rest."
Del Bosque also insisted that Jesus Navas, Alvaro Negredo and Fernando Llorente have nothing to worry about — despite being left out of the squad to face Bolivia.
"Many have chances of getting to the World Cup although they might not feature in this list," he said. "Jesus Navas, Negredo and Llorente could make it."
Del Bosque added that Gerard Deulofeu will be the first player he turns to should an attacker like Costa, who has been struggling with a hamstring problem and was forced off just nine minutes into the Champions League final — be ruled out of the World Cup.
"We have confidence in [Deulofeu]," the Roja coach explained. "He's good on the sides. He's done very well [on loan] at Everton and he's a good solution. If there were any injuries he would be one of the first we'd consider."
Spain squad vs. Bolivia:
Goalkeepers: David de Gea (Manchester United), Pepe Reina (Napoli)
Defenders: Jordi Alba (Barcelona), Raul Albiol (Napoli), Cesar Azpilicueta (Chelsea), Javi Martinez (Bayern Munich), Alberto Moreno (Sevilla), Gerard Pique (Barcelona)
Midfielders: Sergio Busquets (Barcelona), Santi Cazorla (Arsenal), Gerard Deulofeo (Barcelona), Cesc Fabregas (Barcelona), Xavi Hernandez (Barcelona), Andres Iniesta (Barcelona), Ander Iturraspe (Athletic Bilbao), Juan Mata (Manchester United), Pedro (Barcelona), David Silva (Manchester City)
Forwards: Fernando Torres (Chelsea)