The Azzurri's preparations for the tournament have been disrupted by a potentially serious injury to Andrea Barzagli and a betting scandal that may have serious implications in Italian football.
Italy's last pre-Euro friendly ended with a shocking 3-0 defeat at the hands of Russia, but Chiellini believes that his side's chances against the European and World champions cannot be written off.
"We have great motivation and belief that we can win this game," he told Uefa.com. "We will not wait in defence for the odd counterattack because that is not in our nature.
"We will try to respect our opponents and try to do what we have been doing over the past two years – play good football.
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"Spain have proved that even without certain individuals, they are not just playing from memory.
"Even in their recent friendlies they fielded some new players who proved they have as much quality up front [as the usual starters].
"They are a team very much like the one of four years ago that won everything."
Italian sources suggest that Italy coach Cesare Prandelli tested two different tactical systems in Friday's training session, with Davide Astori on stand-by if Barzagli's injury proves to be serious.
"Regardless of the tactics, having the right attitude and the desire to help each other out is the most important thing," the Juventus defender noted.
"Our coach has a great deal of experience and in the next few days he will evaluate the best way for the team to play.
"We have all played at a high level and have played in many different formations so over the next few days we will be able to see what the coach thinks is best for the team.
"For me, though, tactics are all relative, other factors count."