KRAKOW, Poland (Reuters) - Italy's unpredictable Mario Balotelli causes controversy even when he is silenced but coach Cesare Prandelli believes he can become a "champion" if his litany of immaturities are ironed out.

 The 21-year-old striker came on as a substitute and hooked in a superb late goal in the 2-0 win over Ireland on Monday which sent Italy into the Euro 2012 quarter-finals.

 His low-key celebration was typical of his temperamental style, however, and the way Balotelli reacts after scoring his first goal of the tournament, and only his second in 11 Italy games, could be key to his team's chances of going further.

 "What he said (when he scored), he said in English and I didn't understand," defender Leonardo Bonucci, who replaced the injured Giorgio Chiellini, told reporters.

 "So I put my hand in front of his mouth just in case, because Mario is instinctive but that is also his strength."

 Prandelli told a news conference on Tuesday that he would ask the Manchester City forward if his muffled outburst was aimed at the coach who dropped him in favor of Antonio Di Natale.

 "He has to make a leap of quality and he can be a true champion. He has to accept criticism and the bench," Prandelli said.

 "The day he realizes that no one is trying to hurt him and we all want him to do well, he will make progress," he added.

 "I had courage to play him but it was calculated courage. If Balotelli wants to grow up he has to get through these situations."

 Finding the net could inspire Balotelli or conspire to make him even less likely to pass to his team mates.

 Italy's quarter-final opponents in Kiev on Sunday, France, England or Ukraine, will be hoping he is in one of his destructive rather than destructively brilliant moods.

 Prandelli said Balotelli must recognize that he is not playing on his own and has a whole team around him to help, with the group mentality among the Azzurri clearly visible at fulltime against the already eliminated Irish.

 They were overjoyed when they heard Vicente del Bosque's Spain had beaten Croatia 1-0 in the other match, where a 2-2 draw would have sent Italy out and had led Italian media to become obsessed with fears of a possible fix which they call a 'biscuit'.

 Gazzetta dello Sport said 'Thank you Del Bosque' on its front page and Italy captain Gianluigi Buffon agreed.

 "In the last few days I have remained calm because I was convinced Spain, who we owe a big thanks, would behave like a great team," said the goalkeeper, who missed two games in Italy's group-stage exit at the 2010 World Cup as holders.

 "We are staying until June 24 which is the minimum objective we set ourselves."