Torres struck with a penalty as Spain claimed a 2-0 friendly win over Bolivia at the Estadio Ramon Sanchez Pizjuan in Sevilla on Friday.
Del Bosque said the outing felt like a training run for his weakened team, and spoke about the 'trust' he had in Torres.
"We have to consider tonight we played a match, which finishes our first week of training with four sessions and one match," he said.
"Tonight was like a training for the players.
"I trust in Fernando Torres because of that we have brought him. He shown really good things and we are glad how he worked (against Bolivia)."
Del Bosque said Navas' lack of match practice would cost him a place.
"Jesus Navas has been shown an improvement these days. After Premier League finished he had some pain and had to go on treatment," del Bosque said.
"Now he seems to be better but the truth is these last two months he hasn’t played matches. For that reason we would rather choose other player, although he is not 100 per cent out at this point, I have to think with my pillow tonight.
"Diego Costa... is another opened issue because despite having the medical answer we are not fully secure."
