Cristiano Ronaldo's behaviour on his days off is not Juventus's responsibility, according to Andrea Pirlo, after the five-time Ballon d'Or winner allegedly broke coronavirus travel restrictions.

Valle d'Aosta police are investigating whether Ronaldo failed to adhere to Italy's strict COVID-19 protocols by travelling to the area from Piedmont to go skiing with his girlfriend Georgina Rodriguez, as part of her birthday celebrations this week.

Both Valle d'Aosta and Piedmont are listed as "orange zone" regions, with travel between such locations prohibited.

Ronaldo, who tested positive for coronavirus last October, may face a fine if found guilty.

"Cristiano Ronaldo had a day off and on your days off you are free to do what you want," head coach Pirlo told a news conference ahead of Saturday's trip to Sampdoria.

"When they are here they are under my control, but outside of here they are free citizens and can take their own actions."

Weston McKennie has become one of Juve's key performers this season since joining from Schalke, scoring four times across all competitions from midfield since the start of December.

Pirlo believes the 22-year-old United States international has plenty of room for further improvement.

"He is so young he can improve everywhere," he said.

"We were the fastest to sign him in Germany and we are so happy to have him with us.

"He is humble and very keen to improve, especially from a technical point of view. I mean, he is a bit rough in ball control, in his body movements, but he can improve quickly.

"He is a healthy kid, he knows he is not done, he is just at the beginning and being aware of this is already a good starting point."

Pirlo has a clean bill of health, with the exception of forward Paulo Dybala, who is still nursing a knee injury.

Federico Chiesa completed the scoring in the 4-0 Coppa Italia win over SPAL and will start after shaking off an ankle problem.

Alvaro Morata put Juve in front from the penalty spot in midweek - his 13th goal of the campaign - and is ready to go again having been compromised by groin pain of late.

"He played last time and we managed to save him some minutes, so tomorrow he will be at the top of his game," Pirlo added.

"We know him well, he dwells so much on enthusiasm and that is what we need to give him back.

"But he has done well, he knows he is very important for Juventus, so I am more than convinced he will go on at his best."