The World Cup generates billions of dollars in merchandise sales around the globe. One key contributor to this financial boon is the sale of national team jerseys. But in some countries, the best-selling shirt isn't their own. That is turning out to be the early case in South Africa, where fans are snapping up the kit for one of Bafana Bafana's biggest continental rivals. Sias du Plessis reports from Johannesburg.

Global apparel brands like Nike, Adidas, and Puma have launched their national kits at different times leading up to the World Cup, and all of them have seen successful marketing campaigns with good sales of replica shirts. And according to one of Johannesburg's biggest stockists of football shirts, Rashid Cassim Sports, the customer doesn't always stay loyal to one team and often bases their purchasing because of a player.

ASHRAAF ISMAEL RASHID CASSIM SPORTS STAFF MEMBER "One again I think it has to do with the individual, you know, if you take Mo Salah, for instance like you said, he has had the most excellent season for Liverpool and he became the limelight for Liverpool, he became for Adidas himself, so I suppose I won't look at World Cup. I always look at the individual and, obviously, performance club-wise."

Portugal's kit traditionally does very well in terms of sales -- but this year, despite new designs from Brazil, England, Germany, and France -- the kit everyone is trying to get their hands on is that of Nigeria.

ASHRAAF ISMAEL AGAIN "I didn't expect a huge, huge, sell out as to what you think Portugal would be. I think they've taken over globally everything on sales. Nigeria has been number one."

Nike only made a limited number of the special edition Super Eagles kits available globally, and it has been by far the most successful in terms of sales, and the demand continues for the flashy green and white football shirt.

ISMAEL ESSOP RASHID CASSIM SPORTS STAFF MEMBER "It got sold out in five minutes. Guys are going crazy for the Nigeria because of the color, the kit, the design, the style, that's why they like it."

SIAS DU PLESSIS JOHANNESBURG "The Nigeria shirt behind me is the hottest property in football right now. Three millions units are on back order on Nike's website. You can't get your hands on this sought-after top -- it is the last one in South Africa -- and it is already sold. So going on that, judging on the numbers alone, if the World Cup was determined by sales -- Nigeria would win hands down. Sias du Plessis, CGTN, Johannesburg."