"What we can't have is an a la carte line-up, we must face (the match) as part of our preparations for the coming competitions," coach Vicente del Bosque told a news conference as justification for picking a near full-strength side.
Barcelona were unhappy to have their pre-season, including preparations for Saturday's first leg of the Spanish Super Cup against Sevilla, interrupted with the loss of so many players to the national team - plus Lionel Messi who is with Argentina for their friendly against Ireland in Dublin.
"This first star that Spain has obtained will serve to continue reaping successes and now our main objective is Euro 2012. We've come here to win, we did not come as tourists or visitors," the goalkeeper said.
The match, part of Mexico's Bicentennial Independence celebrations, is Spain's first outing since they beat Netherlands 1-0 in the World Cup final in South Africa a month ago.
Mexico, whose World Cup ended with a 3-l loss to Argentina in the quarter-finals, said they dream of denting Spain's crown.
Casillas replied: "If Mexico dent the champions' crown, we'll go back to Spain and there's no problem. We're not going to live off (our world championship)."
Mexico are under interim coach Enrique Meza. They plan to name a replacement for Javier Aguirre, who quit after the World Cup, in December to take charge of the team for next year's Copa America in Argentina and the 2014 World Cup qualifying campaign.
