The UNFP, the union for professional football players in France, have directed a scathing statement towards FIFA president Gianni Infantino - accusing him of "trampling on the physical and mental health of players."
The UNFP called the tournament a "massacre" as they protested the "drastic increase in workloads" in modern football.
The union said: "The incongruity of the situation is not lost on anyone, except of course Gianni Infantino and his courtiers.
"From the top of his ivory tower, which he takes to the four corners of the planet, the FIFA president is not bothered by the fate that the international calendar reserves for the leading players in the game, while ‘his’ Club World Cup proves, to the point of absurdity, that it is urgent to put a stop to this game of massacre.
"It tramples on the physical and mental health of players for a few extra dollars, while making a mockery of, or even ignoring, the collective agreements - La Charte, in France - which, more or less everywhere, provide for an incompressible three-week rest period for footballers between two sports seasons."
The UNFP continued: "The UNFP, like FIFPRO and FIFPRO Europe, has been protesting for years against the drastic increase in workloads, but also against the harmful repercussions for domestic football of a calendar that FIFA alone is still building today.
"And this despite the more than explicit request made by the judges of the European Court in the Diarra ruling, calling on the International Federation to abandon its hegemonic approach and to include the players (players, coaches, doctors) and clubs in the decision-making process on issues that have a direct impact on their profession, whereas today they are simply presented with a fait accompli.