Spain face the vastly-improved South Americans in Malaga on Wednesday and while Del Bosque stressed there could still be changes to his roster before the June tournament in Ukraine and Poland, Torres will struggle to make the cut unless his form rapidly improves.
Losing his place with the world and European champions is the latest setback in a dramatic turnaround for the 27-year-old, who netted Spain's winner in the final of Euro 2008 against Germany but has seen his scoring touch almost completely desert him since joining Chelsea from Liverpool just over a year ago.
"His performances recently have been a bit irregular," Del Bosque told a news conference at the Spanish football federation's headquarters outside Madrid.
"It does not mean that he is not a special and charismatic player, who has represented his country many times," the former Real Madrid coach added.
"He is a lad we appreciate a great deal and it pains me to leave him out but I wanted to be fair to those lads who are pushing for a place."
Del Bosque, who is without Spain's injured all-time top scorer David Villa but hopes to have him back for Euro 2012, said he wanted to reward form players and recalled Valencia striker Roberto Soldado for the first time since June 2007.
He also handed Athletic Bilbao's 19-year-old forward Iker Muniain his first call-up to the senior squad and included strikers Fernando Llorente, also of Bilbao, and Alvaro Negredo of Sevilla.
"Torres should not take his bad run of form as a negative thing but as a stimulus," Del Bosque said. "Football is about being continually alive and the group always has to be alive to compete at the highest level.
"It is in no way a definitive decision. It's a basic list but
