Portuguese side Porto struggled to recruit players ahead of FIFA's expanded Club World Cup, with transfer targets turning down moves specifically to avoid the tournament's additional fixture burden, club president Andre Villas-Boas said.

The FIFA Club World Cup is under way in the United States, with 32 of the world's strongest club teams — from Spain's Real Madrid to South Korea's Ulsan — battling one another.

The Club World Cup has been beset by organisational challenges ahead of the first edition of the revamped 32-team tournament in the U.S.