Richarlison is ineligible to play for Tottenham until the winter window opens on 1 January, after being left out of the club's Premier League squad in favour of injured pair Wilson Odobert and Xavi Simons, the latter of whom is not expected to be fit until February.
Brazilian football lawyer Eduardo Carlezzo, founder of Carlezzo Advogados, told Globo that players in Richarlison's position do have a route to explore, even if he stopped short of commenting on the specifics of this case.
"In theory, and without going into the specific case of Richarlison, it is possible for a player to seek before the FIFA football court a termination for just cause for not having been registered in the competitions in which he will play," he said.
"It is important to note that this type of analysis is done on a case-by-case basis by FIFA, considering all the elements of the contract, the relationship with the player, the competitions he could potentially play and the competitions he will no longer play."
Carlezzo, who has represented multiple appellants before the Court of Arbitration for Sport, said he has previously acted for players in comparable situations.
"We have already acted in cases where, in situations similar to this, we were hired by athletes to seek termination for cause, in cases where the athletes were left aside, unable to compete in any competition, and only training with the B team. There are several precedents that protect the athlete in situations like this."
To return to Spurs' squad even in January, Richarlison would need to replace one of the 17 non-homegrown players already registered. He continues to train away from the first team, posting footage on Instagram hours after Tottenham's 3-2 defeat to Aston Villa, including one sprint clocked at 35.4 km/h that he described as a personal best.
A move to Everton broke down before deadline day, Spurs' pursuit of Iliman Ndiaye lost out to Manchester City, and a return to boyhood club Vasco da Gama in Brazil also collapsed before that country's own transfer window closed earlier this month.