Chile failed Friday in its latest attempt to have its South American rival Ecuador thrown out of soccer’s World Cup, another setback in a high-stakes campaign that threatened to alter the field for the sport’s showcase championship only two months before the tournament’s opening match.

An appeals committee at soccer’s governing body, FIFA, rejected Chile’s newest claim, agreeing with an earlier decision by a disciplinary panel to reject the contention that Ecuador had fielded an ineligible player in several qualification matches. The FIFA appeals panel provided few details on how it reached its decision, though it said the fact that the player, Byron Castillo, holds permanent Ecuadorean citizenship as justification for siding with the original verdict in the case.

Chile contends that Castillo, a 23-year-old defender, was not only born in Colombia but also that he is three years older than stated on the documents used to identify him as Ecuadorean.

Chilean officials said they would make one final attempt to overturn the decision, and strip Ecuador of its place in the tournament, by appealing to the final arbiter of sports disputes, the Lausanne-based Court of Arbitration for Sport.

The fight over the eligibility of Castillo, who plays professionally in Mexico, has for months generated uncertainty over Ecuador’s place at the World Cup, which opens in November. One of four qualifiers from South America, Ecuador is scheduled to face host Qatar in the tournament’s opening game on Nov. 20.

Chile, which filed the appeal that also required Peru’s federation to make a submission, has for weeks fought a public battle to denounce Ecuador and Castillo. Under FIFA rules, fielding an ineligible player could result in a forfeit of any match in which that player took part.

Ecuador finished fourth in South America’s qualifying competition, claiming one of the continent’s four automatic places in the World Cup. But Chile had demanded that Ecuador forfeit the eight qualification games in which Castillo appeared, and that its opponents in those matches be granted three points per game. That outcome, Chilean officials had calculated, would rearrange the qualifying results in South America and lift Chile into fourth place, and into the World Cup, at Ecuador’s expense.

To support its claim that Castillo should not have been allowed to play for Ecuador, Chilean officials scoured public records and social media posts and hired media consultants in Europe to keep attention focused on its case, and its claims. Chile’s federation, meanwhile, sent to FIFA registry documents, including birth certificates and other evidence — even paperwork that, it said, proved where and when Castillo was baptized.

Only days before the appeal hearing, Chilean officials also secured an audio recording from a 2018 investigation in which Castillo appeared; in it, the player seemed to confirm details of his early life in Colombia. That recording was then published by news media.

A FIFA disciplinary committee had rejected the claims against Castillo and Ecuador in June, but the organization’s rules allowed Chile to make its case anew to an appeals body. The hearing took place via video conference on Thursday but Castillo did not take part even though he had been required to join.

“The footballing world heard a player who helped Ecuador qualify for the FIFA World Cup admit he was born in Colombia and that he gained an Ecuadorean passport using false information,” said Jorge Yungue, the general secretary of the Chilean soccer federation. “No wonder he refused to participate.”

“What does it say about appeal committee that, confronted with all this, still they fail to act?” he added in a statement that confirmed Chile’s intention to go to CAS.

Castillo’s background has been shrouded in questions for several years. A wider investigation into player registrations in Ecuador looked into hundreds of cases and resulted in punishments for at least 75 youth players found to have falsified records. Wary of a mistake that might jeopardize Ecuador’s World Cup hopes this year, officials from its national soccer federation had held off on selecting Castillo for the senior national team until this year.

Two years ago, in fact, the president of a special investigation commission convened by the federation appeared to suggest Castillo was Colombian, something that Chilean officials said they had substantiated. Ecuador’s federation finally selected Castillo for the national team after his nationality was recognized and formalized by judicial bodies in that country.

For FIFA, the lingering case has been an additional burden as it grapples with ongoing concerns about the preparedness for Qatar to stage the World Cup. It got an assist from Ecuador in August, when the country’s soccer federation agreed to a request that its game be moved a day earlier so that Qatar could play in the tournament opener on a day free of other matches.