LaLiga has requested the postponement of two games, including Barcelona's trip to Sevilla, after failing to get interim measures in place relating to the release of players for international duty.
The governing body issued an appeal to the Court of Arbitration for Sport (CAS) against the decision taken by FIFA to put in place a two-day extension to the CONMEBOL calendar for fixtures in September and October, a move made amid the complications caused by the coronavirus pandemic.
Due to strict rules that would require players to quarantine for 10 days upon their return, the Premier League refused to release nearly 60 players travelling to 26 countries on the United Kingdom's red list due to COVID-19.
LaLiga announced support to those clubs in Spain that opted not to let individuals travel to play for South American nations in upcoming World Cup qualifiers. A total of 25 players from 13 different teams were due to be involved for their countries.
The organisation also filed a lawsuit against FIFA in the Swiss courts for infraction of competition rules, adding that domestic leagues had already accepted a new match window in January 2022 to accommodate matches disrupted by the global pandemic.
However, CAS denied the interim measures put forward, meaning players will have to be released. LaLiga, which claimed the appeal had been "rejected by the court with no reasoning whatsoever", has reacted by announcing proposed changes to the fixture list for matchweek four.
Barcelona had been due to travel to face Sevilla on September 11, but that game is set to be postponed, along with the top-flight meeting between Villarreal and Deportivo Alaves.
There have also been changes to kick-off times too, with Real Madrid now set to host Celta Vigo in the late game on Sunday. That match could well see the debut of Kylian Mbappe at the newly developed Santiago Bernabeu, should his move from Paris Saint-Germain be completed before the transfer window closes.
LaLiga issued a lengthy statement while announcing the planned alterations to the schedule, as well as a warning that the "senseless situation" could be set to happen again during the October international break, too.
"We emphasise that, due to FIFA's decision, the affected players will rejoin their club teams on Friday after having played three games, and many of them will play league matches on Saturday or Sunday, clearly not being in a position to compete under equal conditions with their clubs," the statement read.
"LaLiga submitted this request to the CAS in defence of the integrity of the LaLiga competition and the rights of clubs affected by players being called up for international duty with CONMEBOL national teams, due to the two-day extension of the FIFA period in September and October 2021.
"Other confederations such as UEFA and CONCACAF did not extend their match calendar despite scheduling the same number of matches (three). These confederations made the effort to adapt their fixture schedule to a maximum of 10 days (until Wednesday), so as not to disrupt national league competitions.
"In addition, this problem occurs after the domestic leagues, together with their clubs, already made an effort to admit a new FIFA window (for all confederations except UEFA) in January 2022, to accommodate match dates previously affected by the pandemic.
"We will encounter this senseless situation once again in October, this time affecting Matchday 9 of LaLiga Santander."
FIFA also issued a statement following the CAS ruling, confirming it now expects all players to be released to play in South America.
"The compromise decision to add two additional days rather than three as requested by the South American confederation CONMEBOL was taken by the competent FIFA body after consulting all relevant stakeholders and after taking into account all relevant circumstances, in particular, the challenges created by the Covid pandemic and especially health considerations for players," the statement read.
"Today's CAS decision confirms the legality of FIFA's decision and entirely rejects the arguments made by Spain's LaLiga.
"On Wednesday, FIFA President Gianni Infantino called for a show of solidarity from all member associations, leagues, and clubs, to do what is right and fair for the global game.
"We now expect the release of players for the upcoming FIFA World Cup qualifiers in South America to occur in accordance with the recent FIFA decision, the legality and legitimacy of which has today been recognised in today's CAS ruling."