Manchester City's success in appealing a two-year UEFA competition ban proves the Court of Arbitration for Sport (CAS) is no longer up to standard, according to La Liga president Javier Tebas.
In February, the Premier League club were accused of committing "serious breaches" of UEFA's Club Licensing and Financial Fair Play (FFP) regulations. They were handed a two-season suspension from European tournaments and fined €30 million (A$50m).
But CAS ruled in City's favour on Monday following the club's appeal, meaning the 2018-19 Premier League champions will be able to compete in the Champions League next season, while their fine was reduced to €10m (A$16m).
Tebas has long been a critic of City and Paris Saint-Germain, routinely accusing them of "ruining" football due to being funded by "petrol money" from the Middle East, suggesting in 2017 that such situations were "financial doping".
And following Monday's ruling, Tebas hit out at CAS and questioned whether they can still be trusted to judge on such matters.
He told reporters: "We have to reassess whether the CAS is the appropriate body to which to appeal institutional decisions in football.
"Switzerland is a country with a great history of arbitration, the CAS is not up to standard."
City CEO Khaldoon Al Mubarak has previously fired back at Tebas for his comments, urging the Spanish official to look back on the history of La Liga and its domination by two clubs before casting judgement on other leagues.