Coach Vincente Del Bosque was expected to trim his provisional 30-man squad for Brazil down to 23 on Sunday, but has instead opted to name 19 players for Friday's match.
The Real and Atletico Madrid players selected in the provisional group earlier this month are omitted after Saturday's Champions League final, with Del Bosque now going to wait until the June 2 deadline to finalise his squad.
"Until June 2 we do not need to give the final list to FIFA so why do it ahead of time?" he said at a press conference on Sunday.
His decision means the likes of Diego Costa - the Atletico striker with a troublesome hamstring - has more time to get fit for the tournament.
Deulofeu is the main beneficiary of Del Bosque's delay, with the Barcelona midfielder now given the chance to position himself at the head of the queue in case of any unexpected pull-outs.
"We trust him and if someone were to pull out tomorrow he would be top of the list," Del Bosque added.
Uncapped Athletic Bilbao defensive midfielder Ander Iturraspe remains in the group, while Chelsea striker Fernando Torres and Manchester United midfielder Juan Mata have a final chance to earn their places in Brazil.
The duo are two of those thought to be primed for the chop but now get an extra chance to persuade Del Bosque otherwise.
Del Bosque also added that the list was not final when asked about Manchester City duo Jesus Navas and Alvaro Negredo and Juventus frontman Fernando Llorente. The trio were named in the 30-man squad but have been omitted to face Bolivia.
The clash takes place in Seville, with Spain also slated for another friendly against El Salvador on June 7 before they start their title defence against Holland six days later.
Spain squad to play Bolivia on Friday: Pepe Reina, David De Gea, Gerard Pique, Raul Albiol, Javi Martinez, Jordi Alba, Cesar Azpilicueta, Alberto Moreno, Zavi Hernandez, Andres Iniesta, Sergio Busquets, Santi Cazorla, Ander Iturraspe, Cesc Fabregas, Juan Mata, David Silva, Pedro Rodriquez, Fernando Torres, Gerard Deulofeu.
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