Much was expected of Spain against the tournament debutants, but De la Fuente's team were unable to find a way past the African side, and need a statement win in Sunday's Group H game with the Saudis to restore some faith.
"We live in a bubble, but criticism motivates us because we have very competitive footballers," De la Fuente told reporters on Saturday.
"And everything that has been said about us, and I'm not really paying attention to this, although some things I do hear here and there, so you never know what I know or I don't know, but this might have an impact on footballers.
"They deal with this well. It's okay that they are up to date. And I can tell you they are really, really eager to go onto the pitch and they will perform very differently tomorrow."
Spain, according to De la Fuente, are not dwelling on the last game and the result and performance have not upset their preparations.
"There's no despair. We are motivated," he said.
"We're eager for tomorrow, to compete again and recover those good feelings we had before.
"It doesn't have an impact on us as professionals. We analysed the match in order to get rid of all doubts and to clarify concepts to see where we did well and our mistakes."
Saudi Arabia also drew their first match, 1-1 with Uruguay, and Spain know they will again need to deal with a side who will likely set up defensively.
"Because of our style, the way we compete, other teams play in a very low block," the manager said.
"We dominate, and those teams have to drop deep. Every team chooses their weapons, and whatever they think suits them best, we have to be more clinical.
"The other day, we weren't sharp. That's something that we've tried to improve. We lacked speed and distribution of the ball."
Once again, Spain's manager faced plenty of questions on Lamine Yamal's fitness. The 18-year-old winger came off the bench against Cape Verde in his first match since April.
"The question is, is Lamine Yamal ready? I can see that in your faces," De la Fuente said.
"He's feeling well, that's the best news. We will see how many minutes he should play. Some of you are talking about him being in the starting lineup, or for how long, the main thing is that he's back."
De la Fuente turns 65 on Sunday, but he has a simple birthday wish.
"My best present would be to be happy, that we are injury-free, we have a good game, and hopefully we win," he said.