Clarence Seedorf and Dutch prince launch a new kind of football Dutch prince Willem Alexander and his wife Maxima joined Dutch football international Clarence Seedorf in Rio on Thursday - to launch a new sport. They took part in a demonstration match of Panna Knockout, a sort of street football played in teams of two to four in three-minute bursts to a hip-hop soundtrack. Organisers hope to hold a World Cup during the football World Cup in 2014. Images and soundbites.