Italy forward Mario Balotelli injured his right knee in training, putting his availability for Monday's European Championship match with Ireland in question.The 21-year-old striker had to abandon training Saturday because of "a minor right knee problem," the Italian football federation said, adding that he will be re-examined by team physician Enrico Castellacci on Sunday.Balotelli has often been bothered by right knee problems. He had meniscus surgery on that knee in Sept. 2010 and was out for two months.The injury could open up a spot for Antonio Di Natale in the starting lineup.Di Natale replaced Balotelli in the second half of Italy's opening two matches, 1-1 draws with Spain and Croatia, and scored against Spain.Italy needs to beat Ireland in its final Group C match and hope for help from Spain and Croatia to advance.Antonio Cassano has been Italy's other starting forward, while other reserves include Sebastian Giovinco, Alessandro Diamanti and Fabio Borini.