Former Liverpool manager Jurgen Klopp believes the Club World Cup is "the worst idea ever implemented in football" because of "serious fears" over player welfare.
The German is now Red Bull's head of global soccer and one of their teams, Red Bull Salzburg, qualified for this summer's tournament in the United States.
Klopp has often complained about players' workload and fixture congestion, and days before the Club World Cup, global players' union Fifpro released a report saying players should be allowed at least a four-week off-season break.
This year's Club World Cup is the first to feature 32 teams and 48 games, and saw Salzburg knocked out in the group stage.