International derbies such as England v Scotland and Brazil v Argentina are often bitter occasions but they are love-ins compared to the enmity and tension surrounding tonight's World Cup qualifier in Belgrade.
The protagonists, Serbia & Montenegro and Bosnia-Herzegovina were at war barely a decade ago. Tonight they meet with a debut appearance in the World Cup finals at stake, a significant prize for any young nation but an especially sweet one if it can be gained at the expense of such opposition.
Security is expected to be tight. The Serbs, with home advantage, a more fêted team, and the knowledge that victory will guarantee a place in Germany, start favourites. The Bosnians, however, have been one of the qualifying tournament's revelations and they know victory will ensure a play-off place, even an automatic one should Spain, the other contenders, falter at home to San Marino.
If Serbia fail to win, Spain, who last missed the finals in 1974, can avoid a play-off by thrashing San Marino away by at least five goals.
As well as Spain and France, who are embroiled in Ireland's group, other major nations in peril include Russia, who must defeat Slovakia in Bratislava to make the play-offs, and the Czechs and Romanians, one of whom will fall tonight.
Then there is Group Two. Turkey, semi-finalists in the last World Cup, and Greece, the Euro 2004 winners, are duelling with Denmark for a play-off place. Turkey are best-placed, but they also have the most difficult fixture, away to Albania.
The same applies to a former holder, Uruguay, in South America. They need only to win to secure a play-off against Australia, but play group leaders Argentina. Chile, worst-placed but at home to an Ecuadorian team that struggle at low altitude, may progress.