Some of pro soccer's biggest teams are playing in the U.S. this summer. That's turning out to be a tough sell.

Sources have told The Athletic that FIFA has been concerned that the opening match has not been selling as well as expected.

Al Ahly have bolstered their attack significantly heading into the Club World Cup. Egypt national team veteran Mahmoud Hassan, more commonly known as Trezeguet, has returned from a loan spell at Trabzonspor, while they added his international teammate Zizo on a free transfer from domestic rivals Zamalek.

Tournament soccer is officially underway this weekend with both the FIFA Club World Cup and the Concacaf Gold Cup, both of which come with plenty of questions for the teams and tournament organizers alike.