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The World Cup may be the best-known soccer tournament on the planet. It may not be the best.

To many fans, the European Championship ranks as the top competition.

This year's continental championship, generally called Euro 2012, kicks off Friday in Warsaw when co-host Poland plays Greece at the National Stadium. Ukraine also will be hosting games.

With only 16 teams instead of 32, many believe the caliber of play at the European Championship exceeds that of the World Cup, which gets diluted by some of the slots apportioned to areas of the globe without strong soccer traditions.

If that sounds arrogant, consider that only one non-European country (Uruguay) has been among the semifinalists at the last two World Cups.

Both tournaments take place every four years, but in alternate even-numbered years. That puts the European Championship, which started in 1960 but became a full-fledged tournament in 1980 when eight teams competed, in the same summer as the Olympics.

For Euro 2012, defending champion Spain — which also won the 2010 World Cup — is the favorite, especially with Xavi Hernandez and Andres Iniesta controlling play. But the Netherlands and Germany are also contenders with their own game-changing players, notably the Dutch trio of Arjen Robben, Robin van Persie and Wesley Sneijder.

Others, like England with Wayne Rooney and Portugal with Cristiano Ronaldo, will also be in the mix.

Hooliganism is always an issue at major soccer tournaments; this year's competition has already been marred by racism concerns and political turmoil in Ukraine.

The 16 teams in the championship — the two co-hosts and 14 other nations that made it through a two-year qualifying tournament — have been split into four groups of four. The top two in each group reach the quarterfinals.

The final will be played on July 1 in Kiev.

Here's a look at the stars, top teams, and a few players who could surprise at Euro 2012.

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BEST PLAYERS

Cristiano Ronaldo

If it wasn't for Lionel Messi ... Ronaldo has been engaged in a hotly disputed fight with Messi to be considered the best player on the planet, but the Argentine, a three-time World Player of the Year, always seems to get the upper hand. The flashy Portugal forward has all the tricks in the book, but has been accused of never producing his best on the international stage. He can change all that here.

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Xavi Hernandez

With his sublime first touch, vision and passing range, the Barcelona star is the beatkeeper of the indomitable Spain team. Voted player of the tournament at Euro 2008, he placed third in the last three World Player of the Year awards. But Xavi's performances in what is likely his final international tournament may be hampered by fitness problems that have dogged his end to the season.

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Andres Iniesta

Xavi's partner in Spain's and Barcelona's midfield and the scorer of the winning goal in the 2010 World Cup final, which shot the balding Iniesta into football immortality. Iniesta's quick feet and effortless dribbling ability makes him stand out, with Xavi describing him as the "complete player."

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Zlatan Ibrahimovic

Moody and temperamental, Ibrahimovic is often left frustrated by the limitations of his Sweden teammates. But it's a different story at club level, where he has played for the top clubs in Spain and Italy. Outrageously skillful and a great scorer, he has a distinctive languid style that his critics attack when things aren't going right. Sweden's only world-class player.

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Mesut Oezil

After two stunning seasons with Real Madrid, comparisons are starting to be drawn between Oezil and French great Zinedine Zidane. Rising to prominence at the 2010 World Cup, the graceful playmaker has the rare ability to make the perfect pass and will be the central component of Germany's attacking play at Euros.

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Robin van Persie

His goal-scoring exploits for Arsenal this season have made Van Persie one of the most sought players in world football. He has a wand of a left foot to rival even the great Messi and will lead the Netherlands as they look to shake off their "underachievers" tag.

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Karim Benzema

France finally has a striker to take over from Thierry Henry. The barrel-chested Benzema's explosive pace and unforgiving finishing saw him emerge as Real Madrid's No. 1 striker by the end of the season. He has been France's leader up front in its sensational recent run of 21 unbeaten games.

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Gianluigi Buffon

Buffon comes into the tournament under a cloud of betting-scam allegations as part of the fallout of the Italian match-fixing scandal, but his reputation as the world's premier goalkeeper remains intact. Tall and athletic, there are no weaknesses in the 34-year-old 2006 World Cup winner's armor. A key member of an Italian backline that had the best defensive record in qualifying.

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Mario Balotelli

Whether it's exploding fireworks in his bathroom or ripping off his jersey to display messages on T-shirts, the enigmatic Balotelli always provides a story. The striker has all the talent in the world and unbelievable coolness under pressure, but has too many off days and could easily implode for Italy this month.

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Wayne Rooney

For Balotelli, read Rooney. His crazy kick-out at a Montenegro defender leaves him suspended for England's first two games at Euros, but there was never a doubt he'd be picked on the squad. The Manchester United striker can be the best player in the world when he's on and is one of England's few world-class stars.

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FAVORITES

Spain

By transforming international football with its tika-taka passing style, top-ranked Spain has been the team to beat for the past four years. The defending world and European champions are classy and stylish, but aren't unbeatable. The Spanish are without leading striker David Villa and defender Carles Puyol because of injury, and there also are fears their Barcelona and Real Madrid stars are tired. Spain is looking to become the first country to retain its European title.

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Germany

A young team which lit up the 2010 World Cup with its fearless attacking play has blossomed into a force set to be Spain's biggest threat at Euro 2012. The Germans score goals for fun and cruised through their qualifying run with 10 straight wins. Question marks remain, however, over whether Germany's eight-strong Bayern Munich contingent recovered from losing the Champions League final in dramatic style to Chelsea.

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Netherlands

The Dutch challenge England for the tag as Europe's biggest underachievers, but also rival Spain and Germany as the most talented team at Euros. Defensively, they look suspect, but they seem unstoppable going forward, led by the lethal Van Persie. Staying true to their expansive, offensive style will be key; they retreated into their shell in the 2010 World Cup final in 2010 and deservedly lost.

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France

The French head into Euro 2012 on the back of an unbeaten run of 21 games and coach Laurent Blanc looks to have unified the squad after its infamous mutiny at the World Cup in South Africa. Much will depend on the influence forwards Franck Ribery and Benzema can have and, like the Dutch, France's defense appears to be its weak link.

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Italy

The Azzurri won the World Cup in 2006 amid the fallout from a match-fixing scandal back home. Could history repeat itself six years later at these Euros? Whether the Italian league crisis unites the squad remains to be seen. Italy has arguably the best defense in the competition and in strikers Antonio Cassano and Balotelli, the Italians have two mercurial players who could light up the tournament.

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FIVE TO WATCH

Alex Oxlade-Chamberlain

The one wild-card pick in an otherwise formulaic England squad, Oxlade-Chamberlain could be the "super sub" that coach Roy Hodgson turns to at Euros. The 18-year-old attacking midfielder has impressed when given an opportunity in his first season at Arsenal with his pace and penetration and is set to be a regular for club and country for years to come.

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Christian Eriksen

Euro 2012 could be the tournament where the 20-year-old Eriksen shines on the international stage, despite Denmark's devilishly difficult group. The stylish Ajax playmaker has been linked with some of the biggest clubs in Europe and this summer could be his shop window to secure that move.

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Robert Lewandowski

An expectant Poland will be relying on its most recent player of the year to reproduce the goal-scoring exploits that fired Borussia Dortmund to a second straight German title this season. Given the co-host's relatively straightforward group, the 23-year-old striker is being tipped by some as a potential winner of the Golden Boot, given to the tournament's top scorer.

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Ibrahim Afellay

The Netherlands have had high expectations for this winger for years and after recently returning to action following an injury-plagued season, he could finally deliver at Euros. With his lightning speed and sweet dribbling skills, Afellay provides a touch of Barcelona play in orange, and his smooth link-up play with Van Persie should earn him a starting berth this tournament.

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Andre Scheurrle

Reportedly high on the shopping list of mega-rich Chelsea owner Roman Abramovich, the 21-year-old Scheurrle is a versatile forward who will be a backup to Lukas Podolski for Germany, but could easily end up taking his spot in the coming years. The emerging star of German club Bayer Leverkusen has the technique and selfless work rate to make himself a star.