Defense wins championships. It’s one of the most widely-used clichés in sports, for good reason. Offense puts people in seats, draws in viewers, and commands the most attention (and in professional sports, often gets the highest salaries), but if you don’t have some semblance of a defense, you will often fall short, even in the Eredivisie!

In soccer, the backbone of a great back line is the goalkeeper. A great keeper can make up for an average defense, but the reverse is very, very rarely true. And at Euro 2012, there will be several quality keepers who will be integral to their teams’ hopes and chances for success, with the top two Euro 2012 betting favorites perhaps boasting the top two keepers in the tournament – and in the world.

Group A

Petr Cech, Czech Republic

The Chelsea #1 has been regarded as one of the world’s best keepers for several seasons now, and it’s easy to forget that he doesn’t even turn 30 for another four months.

He’s made a few crucial errors this season, but there still aren’t many keepers who rank ahead of him, as he’s been so good for so long and is still quite young in keeper years.

Group A, which also includes Greece, Russia, and co-hosts Poland, is a pretty wide-open group, and in matches against quality defensive sides in Greece and Russia where one goal could make all the difference, Cech will need to be at his best to give the Czech Republic their best chance to advance to the quarterfinals.

Group B

Manuel Neuer, Germany

Many, including the great Gianluigi Buffon, think that Neuer is the best keeper in the world already, and many more think that he will hold that mantle soon. Euro 2012 will be an opportunity for Neuer to show just how deserving he is of that title, and if he does, Germany might feel joy, not heartbreak in the final this time around.

His only real weakness is that when he does make a mistake, it tends to be a howler of epic proportions. But those mistakes are very few and very far between, and he more than makes up for it with saves that many a keeper could only make in their dreams.

Germany’s prolific attack would seemingly dim Neuer’s need to be a hero, but when his group includes two other quality attacking sides in the Netherlands and Portugal, it doesn’t hurt to be able to count on someone who’s perhaps the best in the business at his position when shots are coming in from all directions.

Group C

Iker Casillas, Spain

Casillas might not be the first name many think of when considering the success that Real Madrid and Spain have had in his playing career, but given how he’s been a constant for both for a decade, he should be.

Some erroneously think that he’s overrated, but for years, Casillas has as good a claim to being the world’s best keeper as anyone else does, including Group C counterpart Gianluigi Buffon. He’s been awarded that honor by FIFPro and IFFHS four years running, has been the keeper in the UEFA Team of the Year five years running, and he won the Golden Glove at the 2010 World Cup.

It’s not often that you see keepers captaining their side at club level or internationally, and he wears the armband for both one of the world’s top clubs and the world’s best international side. And while it seems like he’s been around almost forever, he’s only 30. Let that sink in for a moment. He’s going to be around for quite a while yet and will make his record for most caps for Spain an almost unbreakable one, and whenever he does hang it up, it‘ll be hard to deny him a place as one of the best keepers of all time. As many stars as Spain have, if they repeat as European champions this summer, Casillas will be as big a reason for it as anyone else in the side.

Group D

Joe Hart, England

English keepers haven’t had the greatest of reputations in recent years, as before Hart, there had been issues with unfulfilled expectations, unconvincing performances, or memorable howlers with the likes of Scott Carson, Ben Foster, Robert Green, and Paul Robinson.

But the Manchester City man has cemented himself as England’s #1 over the last year-plus, and there don’t appear to be any real threats to his standing in regards to talent or potential at present or on the horizon. But to prove that he’s a worthy #1 and not there by default, the 24-year-old needs to put in a disaster-free showing at Euro 2012. There’s a great deal of pressure on him as it is being that it will be his first chance to showcase his skills in a major international tournament, but the added scrutiny that the British media places on its players and the momentous mistakes made by some of his predecessors make his margin for error miniscule. If he successfully deals with the pressure, it will aid England’s hopes to make it past the quarterfinals of a major tournament for the first time since reaching the semifinals as hosts at Euro 1996, and it will also go a long way in restoring a nation’s faith in its keepers.