England open their World Cup campaign against Balotelli's Italy.
"That's dangerous isn't it because you never know, will he turn up, will he not?" says Cahill. "He's got the potential to stick it into the top corner from 30 yards. He's an unpredictable player but on his day he's one of the best.
"I played against him a couple of times at City and he's been tough. I played against him another time when he came off after 60, 70 minutes. Unpredictable. He can be world class. They're just dangerous players but you come up against them every game."
For the big stories and the banter follow us on Twitter: @tribalfootball