Adrian Mutu must pay Chelsea more than ?17 million ($20.7 million) in compensation after losing his final appeal in a five-year legal case over a positive cocaine test.
The Swiss Federal Court on Monday followed the Court of Arbitration for Sport and FIFA in ruling that Mutu must pay the sum - a record for a football case.
It was unclear whether the Romania international will be able to pay the full amount.
Romanian television reported last year that the total compensation would likely bankrupt the 31-year-old player, who is currently serving a nine-month doping ban in Italy.
Chelsea terminated Mutu's contract after he failed a drug test for cocaine in 2004. He still had nearly four years left on his contract with the Premier League club.
Chelsea received no compensation when Mutu rebuilt his career in Italy, first with Juventus and since 2006 with Fiorentina.
FIFA awarded damages to Chelsea because Mutu breached his contract, a decision upheld by CAS.
Mutu took his appeals to Switzerland's supreme court, which ruled that CAS followed correct legal process when it dismissed Mutu's challenge to the FIFA decision.
The federal panel also considered whether the amount of compensation awarded to Chelsea violated legal principles.
``It reached the conclusion that this was not the case and the Romanian footballer's appeal was unfounded,'' the court said in a statement.
Mutu must pay ?17,173,990 plus annual interest of 5 percent applied from Sept. 12, 2008. The federal panel also ordered him to pay court costs totaling 145,000 Swiss francs ($127,000; ?104,000).
Mutu's assets are worth ?14 million ($17 million), according to Romanian daily Cotidianul, which added that he will have to borrow to pay the fine.
The paper reported that ?10 million ($12.1 million) of Mutu's assets comes from football contracts. He also holds property assets with an apartment in Bucharest, another in Miami and one in Florence, Italy where he plays.
Mutu also has shares in a clothing line and agreed advertising contracts with olive oil and wine companies in Italy.
Chelsea and its Russian owner, Roman Abramovich, could agree to negotiate a lower sum after an expensive fight at five separate legal bodies.
Mutu's agent Victor Becali said Monday that ``surely there are other avenues where we can contest'' the verdict and added his client would consider doing so in a European court.
Mutu's career prospects also have dimmed while waiting for the final court judgment.
He is currently suspended for nine months after twice testing positive for the banned stimulant sibutramine after Italian league and cup matches in January.
Mutu is expected to leave Fiorentina before he can resume playing on Oct. 29.
The federal ruling ends a case that has passed between English football authorities and Swiss-based legal panels for more than five years.
Mutu, then 24, arrived at Chelsea when billionaire Abramovich funded a spending spree after buying the club in 2003.
Chelsea paid ?22.5 million (then 15 million pounds) to sign the striker from Italian club Parma, but 14 months later he tested positive for cocaine. He did not challenge the test result.
The English Football Association banned Mutu for seven months and Chelsea terminated his contract.
Mutu first appealed to the English Premier League, then lost again at CAS in Dec. 2005.
By then, he had signed as a free agent for Juventus, which sold him one season later for ?8 million to Fiorentina.
Chelsea then asked FIFA to use its rules on breach of contract and award compensation based on the lost transfer fee and unserved time on Mutu's lucrative deal.
FIFA said in 2006 that it had no power to decide, but CAS backed Chelsea and returned the case to Zurich.
FIFA's disputes panel settled on the ?17.2 million figure and its appeals body agreed after Mutu launched another challenge.
A third CAS panel heard the case and last July dismissed Mutu's request to annul the award.
Although Lausanne-based CAS is world sport's highest court, it is governed by Swiss civil law and Mutu was able to petition the country's supreme court.
