Fiorentina striker Adrian Mutu tested positive for a banned substance after the Serie A fixture against Bari on 10 January, the Italian Olympic Committee (CONI) has announced.
Traces of the anti-obesity drug sibutramine were found in the Romanian international's A urine sample, given after the 2-1 victory in Florence earlier this month, in which he scored.
In a statement, Fiorentina said: "After taking note of the CONI statement about Mutu's doping test failure, ACF Fiorentina – while confirming the club's firm opposition to the use of any kind of banned substance, even as a dietary supplement – believe in Adrian Mutu's good faith and will try to clear up this situation as soon as possible."
The 31-year-old Mutu was banned for seven months by the English Football Association (FA) in November 2004, a suspension extended worldwide by world football's governing body FIFA, after testing positive for cocaine during his time at Chelsea, who sacked the player.
If Mutu is found guilty of a second offence, according to the code set out by the World Anti-Doping Authority (WADA), he risks a suspension of between one and four years.
Today's news breaks as a Swiss Federal Court is nearing a ruling on Mutu's appeal against the Court of Arbitration for Sport (CAS), which said he must pay Chelsea 17million euros for breach of contract - as ordered by FIFA's Dispute Resolution Chamber last year.
The former Parma and Juventus striker has scored four goals in eleven Serie A games this season, and three in four UEFA Champions League outings as the Viola qualified for the first knockout round.