A season with a Club World Cup often spells doom, but Barcelona could avoid it by using fresh players.
Winning the Champions League is nothing short of amazing, but it does bring one significant problem to the next season: The Club World Cup, and to a lesser extent, the European Super Cup.
In Spain, winning La Liga or the Copa Del Rey also brings two more games in the form of the Spanish Super Cup. Overall, these 5 additional games, plus additional travel, present a burden for teams seeking to repeat as European champions. No team has done so in the Champions League era.