Juventus midfielder Paul Pogba has been provisionally suspended from playing because of an anti-doping offence.
Italy's national anti-doping tribunal (Nado) said Pogba returned a test with elevated levels of testosterone after Juve's 3-0 win at Udinese on 20 August.
France international Pogba, 30, was an unused substitute but was selected at random for post-match drug testing.
If found guilty of doping, he could face a ban of between two and four years.
Juventus said in a statement: "Juventus Football Club announces that today, 11 September, 2023, the footballer Paul Labile Pogba received a precautionary suspension order from the National Anti-Doping Tribunal following the results of tests carried out on 20 August, 2023.
"The club reserves the right to consider the next procedural steps."
Pogba's agent, Rafaela Pimenta, said she was "awaiting the second sample and cannot have an opinion before the results".
"What is certain is that Paul Pogba never wanted to break a rule," Pimenta added.
Nado said Pogba had violated anti-doping rules when they found the prohibited substance "non-endogenous testosterone metabolites" and the results were "consistent with the exogenous origin of the target compounds".
Testosterone is a hormone that increases the endurance of athletes.
Pogba has three days to produce a counter-analysis of the result to Nado.
Juventus re-signed Pogba on a four-year deal in July 2022 after the player ran down his contract at Manchester United and left as a free agent.
However, Pogba's return to Turin has been beset by persistent injury problems which also saw him miss last year's World Cup in Qatar.
Pogba has played a combined total of 51 minutes as a substitute this season in games with Bologna and Empoli.
Last season he managed 108 minutes over six Serie A games, three brief appearances and one assist in the Europa League, and 11 minutes in the Coppa Italia - a total of 162 minutes and no goals.
Pogba's injury problems resurfaced recently, with Juventus boss Massimo Allegri saying the player picked up a minor back problem following his appearance against Empoli.