Spain, the world's best team for the past four years, are favourites as they try to retain the European Championship but the question for punters is whether their momentum has slowed or even gone into reverse. No country has retained the Euro title since its inception in 1960 and only two reigning champions have even reached the final - the Soviet Union lost 2-1 to Spain in 1964 and West Germany were beaten on penalties by Czechoslovakia in 1976.
And only two beaten finalists have returned to take the title four years later - West Germany in 1980 and the unified Germany in 1996. That gives hope to tournament second favourites Germany, runners-up to Spain in 2008, but it also emphasises the cyclical nature of international football.
It is difficult to stay at the top, which makes Spain's status as the reigning world and European champions all the more impressive. At the same time, Barcelona have been the dominant team on the European club scene and that's no coincidence because the Catalan club has supplied the heartbeat of the national side with Xavi and Andres Iniesta.
Yet there has been the sense that an era has ended for Barcelona and the same could happen to Spain, who likewise have to cope with the ageing of Xavi and David Villa's absence through injury.
Germany are more of a team on the up, having done well with their youngsters at the 2010 World Cup, and they usually give their backers a good run for their money. At the past three major tournaments (World Cup and Euros) they have finished third, second and third, and their record at the Euros is second to none.
That is especially true of the Euros when the host country has not won - as may well be the case with this year's joint hosts Ukraine and Poland. Of the 10 tournaments won by an outside country, Germany (or West Germany) have appeared in the final six times and won three.
The problem for Germany is they are drawn in the strongest group (B), which features four countries from the world's top 10. All four are higher-ranked than the teams in group A, which means the countries that come out of group B will have a good chance of going a long way in the competition because they face group A teams in the first knockout round.