The reigning world champions have an embarrassment of riches, especially in midfield, and Del Bosque revealed he was still unsure as to who would make his final 23 to travel to Brazil next month.
"Of course I have doubts, they're nice to have, but we have many certainties and no doubt we will resolve everything in time," he is quoted as saying by Mundo Deportivo.
Del Bosque also took time to discuss the strength of the Spanish domestic league after an impressive season in Europe that has seen La Liga clubs take up three of the four final slots in the UEFA Champions League and Europa League.
"It's good that there is competition at the top and the bottom," he added. "It's very hard to predict. It's a league that values what football is.
"At club level our teams are the best with two (Real and Atletico Madrid) Spanish clubs in the Champions League final and one (Sevilla) in the Europa League.
"I don't think we could do any more and we'll see if we can maintain this level."
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