Mata also thought the team would have enough time to adapt after traveling to Rio late Monday.
"We're happy training here, and I don't think just because the temperature will rise a few degrees will be a determining factor or an excuse," he said.
Spain has tended to start recent tournaments slowly, losing to Switzerland in its 2010 World Cup opener before drawing against Italy in its first Euro 2012 game. But both times it went on to lift the trophy.
This time, however, it finds itself in an uphill struggle in perhaps the tournament's toughest group.
Pedro said Spain would be keeping an eye on his Barcelona teammate Alexis Sanchez, who guided Chile to its opening 3-1 victory over Australia.
"Alexis is the big star of that team, he assumes responsibility for leading it," Pedro said. "His role at Barcelona is different. Chile relies on him more, and he had a great season and scored a lot of goals."
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