The European champions play fellow World Cup competitors South Korea in Innsbruck on Thursday looking for an improved performance from their lacklustre 3-2 win over Saudi Arabia last weekend.
"Cesc is fine, he has been training better every day and tomorrow he will be one of the ones to play," Del Bosque told a news conference in Austria.
"He is very well. Although he missed a session yesterday it wasn't because he had a problem but as a precaution. We need to be careful with him," said Del Bosque.
"We have no doubt he will be ready for us on June 16 (against Group H rivals Switzerland) in perfect condition. We aren't going to take risks. We'll use him when the medical staff and the player are happy."
"You could say we have had some demanding training sessions. We have perhaps focused on other things more than tomorrow's game," Del Bosque said.
"We have used the time well, we are pleased with how things are going."
Spain's final warm-up is against Poland next Tuesday. Also featuring in Group H in South Africa are Honduras and Chile.
