World Cup 2014: 'I know if I make one slip Balotelli can win the game,' says Gary Cahill

The Chelsea defender is playing in his first international tournament but is not worried by the prospect of facing Italy and their unpredictable striker

Gary Cahill is reflecting on the life of a centre-half at the elite level, a world where the margins are so fine, where the tiniest slip in concentration means that a goal can be conceded and a game can be lost. He considers the task that awaits him in six days' time when he will line up against Italy and Mario Balotelli in Manaus.

The problem with Balotelli, of course, is one never knows which Mario will turn up on any given day or, more pertinently, on Saturday in England's first World Cup final group game.

"That's dangerous isn't it?" Cahill reflects. "He's got potential to stick it in the top corner from 30 yards. He's an unpredictable player but on his day obviously one of the best. Another dangerous player, but you come up against them every game you play.

"I played against him a couple of times at Manchester City and he was tough. Another time he came off after 60 minutes. Unpredictable. At times he can be world class. But he's certainly one player to watch out for.

"That's the nature of my position. Many times I've come off the pitch and thought: 'I was unbelievable there for 87 minutes'. All of a sudden you switch off, or a cross comes in, the striker scores and it wrecks your whole game. I think that's just the nature of my position as Joe [Hart] or Ben [Foster] or Fraser [Forster] would say."

Cahill, 28, is now England's most established centre-half. He is a Champions' League and Europa League winner at Chelsea, who have just sold another centre-half, David Luiz, one of Brazil's most recognisable stars, but kept their rock-solid Englishman. Of course, Luiz attracted a premium price and Cahill is a precious homegrown player, but even so it demonstrates just how far he has come.

In many respects he is one of the unsung success stories of English football. A modest, unflashy type, he took his time coming through. Aston Villa never saw the potential in him and Gary Megson signed him at Bolton Wanderers where he played four years before Chelsea made their move in January 2012.

It is interesting to hear him describe how the challenge has changed. At Bolton it was a case of impressing in a team that, against the big boys, would, almost inevitably concede at some point. Playing for one of Europe's elite clubs, he is rarely under that kind of constant pressure but he knows that, in his own words, "you might have three or four crucial things in a game to do and if you do them right, you'll keep a clean sheet."

Not that he is going about wide-eyed with wonder at his new status. He has believed from the start that he was good enough. "I have played in the Premier League since I began. I took a step back at Villa when I had to move but it was just about having that opportunity. At Bolton I played week-in, week-out and from there Chelsea came in and gave me the opportunity to go to that next level. I am thankful for that but I felt like I could do it. I just needed the opportunity."

He was behind the likes of Michael Dawson and Matt Upson for the 2010 World Cup finals squad and never got close. Since that tournament he has been in every England squad when he has been fit, and then on the brink of Euro 2012 he was shoved by Dries Mertens in the last warm-up game against Belgium, crashed into Hart and broke his jaw. As a result, Brazil will be his first international tournament.

"I try not to think about it because that was a piece of bad luck in my career and I was about to get on the plane," he says. "There is no reason why I should think about it. I have gone through this season, touch wood, with very few injuries."

As a kid he supported Sheffield Wednesday and watched Des Walker, an English centre-half who had made his name internationally at the 1990 World Cup finals as an unflappable defender. Not a bad role model. "I thought he was a great athlete as well," Cahill recalls, "he was quick, wasn't he?"

It has been a long journey to get here but Cahill has never disappointed each time he has gone up a level.

"I'm proud of what I've achieved. I'm proud that I've worked hard and gone through those progressions," he says. "It's not always the fact that you start at Manchester United as a kid and crack on and play for England. Sometimes the progression is different."