Major tournaments often spring major surprises, from South Korea at World Cup 2002 to Greece at Euro 2004, and Turkey at Euro 2008.
This summer's tournament sees all the major European nations in attendance - Switzerland are the highest ranked absentee at 18 in the FIFA rankings - but an unlikely contender could still upset the odds in Poland and Ukraine.
A quick glance through the 16 competitors reveals the strength in depth of this year's competition. Germany, Holland and Spain - three of the world's top four teams - are rightly favourites, and Italy, France and England will all feel they have a chance.
Beyond the perennial contenders lies those nations that will take heart from the Greek precedent of 2004. Each possessing one or two standout players, and ably assisted by a enthusiastic supporting cast, these four teams will be attempt to become this tournament's surprise package.
Group A: Poland
Poland qualified for their first European Championships in 2008, beating Portugal into first place as they climbed up to 16th in the world. But the tournament was a disappointment as Poland crashed out in the group stages with just a single point.
On home soil, this summer should be different. The Borussia Dortmund trio of Lukasz Piszczek, Kuba Blaszczykowski, and Robert Lewandowski will be crucial to their success, and Lewandowski especially carries Poland's goalscoring burden largely unassisted.
Wojciech Szczesny will have to be on top form for Franciszek Smuda's side to have a chance, but they will be disappointed if they fail to get out of the group stage. Group A is the weakest of the four, with Poland due to take on Czech Republic, Russia, and Greece.
Russia will be favourites to finish top, but it's a free for all for second spot. Greece finished their qualifying group unbeaten, but their anemic goalscoring record could prove to be their downfall. A goalscorer is vital to any team, and Lewandowski is a better bet than Giorgos Samaras or Dimitris Salpingidis.
Group B: Portugal
The 2004 finalists lost to Germany at the quarter-final stage in 2008, and will be looking for revenge in Group B this time around. Qualification into the knockout rounds will be tricky, with the Germans taking their place alongside 2010 World Cup runners-up Netherlands and 1992 champions Denmark.
The Danes pipped Portugal to top spot in qualification Group H but Portugal's goalscoring ability - they scored 21 in qualifying - gives them the edge in Ukraine and Poland.
The Portuguese always bring a hugely talented team to international tournaments, and this summer is no exception. Any side with Cristiano Ronaldo stands a chance, and the Real Madrid star is ably supported by a decent midfield class, including former-United teammate Nani, Porto midfielder Joao Moutinho, and the adventurous full-back/winger Fabio Coentrao.
Dislodging Germany or the Netherlands will require a monumental effort, but should they qualify they would face a Group A opponent in the quarter-final, and would surely back themselves against any of those four contenders.
Group C: Croatia
With Italy preoccupied with yet another match-fixing scandal, Ireland and Croatia will be greedily eying the second spot behind Spain.
Croatia look best-placed to capitalise and run deep into the tournament, and with Luka Modric in midfield, they boast one of the few players capable of keeping the ball off Spain.
But for Slavan Bilic's side to shine, Everton striker Nikica Jelavic will need to replicate his fine goalscoring form since his January move from the SPL, and Darijo Srna and Ognjen Vukojevic will need to stay healthy.
Croatia possess the attacking creativity offered by qualifying group F top scorer Niko Kranjcar and the ability to choose from four top strikers, Jelavic, Ivica Olic, Eduardo and Mario Manzukic.
Group D: Sweden
Sweden qualified three points behind the Netherlands in group E, and even beat the Dutch 3-2 without Zlatan Ibrahimovic. Their highly combustible but undoubtedly talented AC Milan forward is capable of class and farce in equal measure, but this time has a supporting cast capable of sharing the burden.
Ola Toivonen has been in good form in Holland and Kim Kallstrom is a shrewd midfield operator. Andreas Isaksson offers a safe pair of hands, Blackburn's Olsson twins bring pace, and Rasmus Elm is highly-rated by a number of Europe's top bosses.
The Swedes always bring a large band of traveling fans, and they stand a decent chance of watching their side progress into the knockout rounds this year. With pessimism pervading the French and English camps, the door is open for Sweden or Ukraine to steal through into the latter rounds.
A win against co-hosts Ukraine in their opening match is vital for Sweden, and with three points in the bag, they could pose a major threat to England and France's qualification hopes.
Who's your outside bet for a run into the later rounds of the tournament? A Tomas Rosicky-inspired Czech Republic? Denmark's youthful brigade led by Manchester United target Cristian Eriksen? Have your say on the contenders and leave your comment below...