UYO, Nigeria—Weeks before the 2018 FIFA World Cup was due to kick off in Russia, a woman met Blessing and Mfon at the Godswill Akpabio Stadium in the southern Nigeria city of Uyo. The two young sisters had gone there to watch Nigeria play Spain’s Atletico Madrid in a warmup match ahead of the global soccer fiesta in which this West African nation is proud to participate, and the woman, in her 40s, seemed to be a devoted fan.

“We sat beside her during the match, and we were all analyzing the performance of the [Nigerian] team together,” Blessing, who is 19 and the older of the two siblings, told The Daily Beast. “After the match, she asked us if we would like to go watch the World Cup in Russia and work there after the tournament.”

Russia is open to foreigners with just a single match ticket and a FAN ID, which is available online to confirmed ticket holders. Once you’re in, you can stay legally until July 25, which is 10 days after the end of the competition.

While this is good news for soccer fans visiting the country, it is equally an opportunity for traffickers to do big business.

Blessing and Mfon were told their travel to Russia would be taken care of and that they would get jobs in Moscow as social workers for a nongovernmental organization dealing with traumatized athletes once the World Cup was over. The girls were told it would take about six months to pay back the cost of the journey to Russia, put at $20,000 each, after which they could keep all the money they made.

“We took her to our parents, and she told them the same thing,” Blessing said. “She said she had slots for 20 Nigerian girls and was looking to take girls from all regions of Nigeria with a passion for sports.”

No one suspected the woman was a human trafficker because she showed documents appearing to link her to a number of humanitarian organizations in Russia, and she hailed from the same wider community as the family of Blessing and Mfon, which gave the parents of the girls the impression that she wouldn’t hurt her kindred.

“Besides, when we hear about trafficking we hear of Italy and not Russia,” Mfon, 17, told The Daily Beast. “The news on Russia is always about the president [Vladimir Putin], not trafficking.”

The sisters were due to depart Lagos for Moscow on the eve of the opening match of the World Cup this week and had packed their bags well ahead of time. But just days before departure, their parents stumbled on news on local TV that authorities had rescued nine young girls and one boy who were being trafficked to Russia. On realizing that their daughters could be victims of human trafficking, Blessing and Mfon’s parents asked them to cancel their travel plans.

“Our father said he had read further about trafficking to Russia and was convinced we were going to be trafficked,” Mfon said. “He has been calling the woman since he saw the news but she has not been picking up her calls.”

In the operation that alerted Blessing and Mfon’s parents, five suspects, including a Nigerian quarantine officer and a policeman, were picked up by security personnel at the Lagos airport for allegedly facilitating the travel of the nine girls and a boy, who were stopped by officers while trying to board a Turkish Airlines flight from Lagos to Moscow. The victims, who are now in a government-provided shelter for victims of human trafficking, were in possession of football supporter ID cards in order to appear as if they were just spectators heading to Russia for the World Cup.

They were not the only potential victims of human trafficking stopped from traveling to Russia. Five other children were prevented from boarding a flight to Moscow when officials at the airport discovered that they had one-way tickets.

Nigeria’s anti-trafficking agency, NAPTIP, warned last month that cartels were planning to take advantage of a move by Russia to let spectators enter the country with just a ticket and a fan pass to traffic women into Moscow.

“It has come to the knowledge of the agency that some dishonest persons and networks of human traffickers have concluded plans to use the forthcoming World Cup to recruit and traffic Nigerian youths out of the country,” Julie Okah-Donli, NAPTIP director-general, said at a press briefing in the capital, Abuja, at the end of May. “Their plot is to set up unregistered football supporters’ clubs, unofficial government delegations as well as unrecognized youth bodies to collect huge money from desperate youths and ferry them out of the country in the name of the World Cup.”

Trafficking of Nigerian women to Russia isn’t a new phenomenon. Some 2,000 to 3,000 Nigerian girls reportedly are taken to Russia every year for prostitution, with many traveling on student visas. The number increased during the Confederations Cup, with documented cases of dozens of Nigerian women brought to the tournament last year, when the visa-free entry system was tried out.

“Not going to Russia with that woman is the best thing that could have happened to us,” said Blessing. “We can now relax at home and enjoy the World Cup!”