Once considered among the top midfielders in world soccer, Paul Pogba's career risks a premature ending after the French World Cup winner tested positive for testosterone.
The exam was carried out after the Juventus' game at Udinese on August 20. Pogba did not play in the Serie A match but was on Juve's bench.
Nado Italia, the anti-doping agency, said Pogba was suspended provisionally with immediate effect.
Pending a trial and testing of a backup "B" sample, he risks a suspension of up to four years.
If the backup sample confirms the positive test, the 30-year-old Pogba could get a lesser ban if he cooperates with authorities.
There was no immediate comment from Pogba or Juventus.
The agency said Pogba had violated anti-doping rules when they found the prohibited substance "non-endogenous testosterone metabolites", adding that the results were "consistent with the exogenous origin of the target compounds".
It's another negative note for a player who has been bothered by injuries ever since rejoining Juventus from Manchester United a little more than a year ago.
He was ruled out of France's run to the World Cup final last year due to a knee injury and played in only six Serie A matches for Juventus last season.
There's also been a police investigation ongoing in France into allegations that Pogba was targeted by extortionists — including by his older brother, Mathias, who has denied any wrongdoing.
The latest blow to Juventus follows last season being marred by inquiries into false accounting and irregular reporting of salary payments. The legal cases resulted in the Turin club being removed by UEFA from European competition this season.
Having started his career at United and then gone to Juventus and back to Manchester, Pogba was known for his versatility, physicality and eye for the goal.
When he returned to United in 2016, the Manchester club paid Juventus a then world-record transfer fee of 105 million euros ($A176 million) but he rarely fulfilled the huge expectations.