"He is a very complete player. Because of his physique he may bring things that others don't. In a tight game you can send a ball forward and he fights well for it, lays it on and holds the ball very well too," Casillas told a news conference on Tuesday.
"The most recent example was in the World Cup (second round game) against Portugal, when we couldn't find openings and he came in and changed the match," the keeper added.
"Since that match, he has progressed even more. That day he was very important for us and since then he has taken off and is now well regarded since has upped his game," coach Vicente Del Bosque said.
Llorente's form has attracted the interest of several top European clubs and Spanish sports daily AS on Tuesday linked him with a move to La Liga leaders Real Madrid.
Spain's main injury doubt apart from Torres is midfielder Xavi, who has been struggling with an Achilles problem this season and missed last month's internationals.
"Xavi is here well and in good spirits... but we have not fixed how many minutes he will play. In principle, if he can play 90 minutes, he will, but we will not do anything that can harm his fitness," Del Bosque said.
The friendly is being held as part of the effort to promote the joint bid by the two countries to host the 2018 World Cup. FIFA's decision is due on December 2.
