Mutu rebuilt his career in Italy after being sacked by Chelsea
Adrian Mutu must pay Chelsea £14.65m after losing his appeal against a Fifa ruling for a breach of contract.
The striker, who cost the Blues £15m in 2003, was sacked a year later after he tested positive for cocaine and given a seven-month worldwide football ban.
Fifa issued the ruling last year but Mutu described it as "inhumane and unjust" and said he would appeal.
However, the Court of Arbitration for Sport (Cas) has ruled against the 30-year-old, who now plays for Fiorentina.
"The Cas panel concluded that the appeal brought by the player was to be dismissed and the measure of damages, as awarded by Fifa's Dispute Resolution Chamber (DRC), was to be confirmed," said a Cas statement.
"Adrian Mutu must therefore pay 17,173,990 euros to Chelsea FC."
The compensation figure, based on lost earnings, was calculated on the length of time Mutu's contract had left to run, and was the highest ever handed down by Fifa.
After being sacked by Chelsea and serving his ban, the Romanian joined Juventus in January 2005, and at the end of the following season he moved to his current side, Fiorentina.
When Fifa announced its verdict, Chelsea welcomed it, calling it "a very significant decision for football".
The Chelsea statement continued: "Not only did the Dispute Resolution Chamber make us a very significant monetary award, it also recognised the damaging effect incidents involving drugs have on football and the responsibility we all have in this area."
The latest ruling is third time that Cas has been involved in the case.
"In 2005, Cas confirmed the decision of the Football Association Premier League Appeals Committee finding that, because of a positive doping test, Mutu had committed a breach of the employment contract without just cause," added the Cas statement.
"In 2007, Cas set aside a first decision by the DRC denying jurisdiction and referred the matter back to Fifa to determine and impose the appropriate sporting sanction and/or order for compensation arising out of the dispute."
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