(Read about soccer juju in Côte d'Ivoire (Ivory Coast) in National Geographic magazine.)
"This service is something that is not to be given away for free," Becker said. "Some teams spend so much money on juju that they may be unable to afford traveling to away games."
Most practices seem to be directed at weakening the opponents' spirits.
One well-known technique involves smearing the blood of a pig in the opponents' locker room to scare younger players.
A more extreme practice stipulates that a cow should be buried alive on the field in front of the opponents' goal.
"This is meant to suck the power out of the opponents," Becker said.
A second pair of goalkeeping gloves can be hung in the net to ensure the opponents' goals don't get through. Bits of animals or plants can also be burned near the goal or strewn there in the form of magic powder.
"It's a competitive business," Becker said. "The witch doctors are always trying to come up with new things to try to outdo each other."
When running onto the field, teams may avoid their usual route, because it could be hexed. Or the team may try and weaken the opponents' magic by entering the field backward.
Such seemingly odd behaviors are not limited to African national teamssuperstitions are common in soccer the world over.
Many European and South American soccer stars, including those currently playing in the World Cup, adhere to strict pregame rituals.
England defender John Terry, for example, says he always sits in the same place on the bus traveling to the game. He also must tie the tapes around his socks that hold shin guards in place three times before a game.
During this World Cup, Spanish striker Raul Gonzalez was reportedly berated for turning up at practice wearing a yellow T-shirt.
His coach, Luis Aragones, considers yellow bad luck. (France went on to knock Spain out of the cup on Tuesday.)
Before every game Argentina's former coach Carlos Bilardo used to borrow toothpaste from one of his players. He started the ritual before Argentina's first match in the 1986 World Cup, which his team went on to win.
Former Italy coach Giovanni Trappatoni could be seen sprinkling holy water on the playing field from a bottle provided by his sister, a nun.
Juju Dying Out?
Kwabena Ofori is the president of Capital Sports FC, a second-division soccer club in Ghana.
He says juju practices are becoming increasingly uncommon.
"These traditional practices are dying out, along with traditional medicine," he said.
"Players who think they may have a broken bone know they have to go and have it x-rayed at a hospital, not wrapped by a traditional healer."
Soccer witchcraft remains popular in neighboring Benin, which only proves that it doesn't work, Ofori says.
"Benin never gets to the World Cup," he said.
According to Ghana's Ministry of Education and Sports, a woman asked to be taken to the national team's training camp before the World Cup. She claimed to be the queen of all witches of Ghana's Nzemaland region.
The sorceress planned to "offer spiritual support and ward off all evil." The offer was turned down.
On Tuesday Ghana lost to Brazil, zero to three, and was eliminated from the cup.
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