“Yes, the players can have their wives and family come to visit them at the World Cup. […] However, I won’t allow them to have Russian girls, no, no, no. Only captain Mikel who has a Russian partner can come with her,” Gernot Rorh, the Nigerian team’s coach said.

Here's the complete warning from Gernot Rorh... http://nigeriarendezvous.com/nigerian-footballers-banned-from-having-sex-with-russian-women-at-2018-world-cup/