Mata, United's record signing, has experienced a frustrating start to his United career but was ineligible for their pitiful Champions League defeat to Olympiakos on Tuesday, having played in the competition for Chelsea.
Torres, the most expensive player in English football history, struck for the Blues in their 1-1 draw at Galatasaray midweek but is another victim of Spain's enviable embarrassment of riches and Del Bosque's tiki-taka approach.
Who'll be at the 2014 World Cup?
Diego Costa, Alvaro Negredo and Pedro are the only strikers included in the squad, with David Villa, La Roja's all-time top scorer, Fernando Llorente and Roberto Soldado absent.
Gerard Piqué is out injured and there is no room for Alvaro Arbeloa, Jesé, or centurion Carles Puyol, either.
Both Mata and Torres have stiff tasks ahead of them if they are to force their way into Del Bosque's 23-man World Cup party.
Goalkeepers: Iker Casillas, Pepe Reina, Victor Valdés
Defenders: Juanfran, Sergio Ramos, Jordi Alba, Cesar Azpilicueta, Raúl Albiol
Midfieldes: Xabi Alonso, Sergio Busquets, Xavi, Koke, Thiago Alcântara, Andrés Iniesta, Jesús Navas, Santi Cazorla, Cesc Fàbregas, David Silva
Forwards: Diego Costa, Alvaro Negredo, Pedro