Pogba said he will appeal against the decision and would "never knowingly" dope after tests found elevated levels of testosterone in his system.

"It's very sad both on a human level and for football," said Allegri before Sunday's Serie A match at Napoli.

"We are losing an extraordinary player.

"I was lucky enough to work with him, coach him, and it's very difficult to find players like him... he's a fantastic guy."

Pogba, 30, was a key midfielder in the Juventus side who won the Serie A title under Allegri in 2015 and 2016, after which he signed for Manchester United for a second time in a then-world record £89m deal.

Allegri went on to guide Juventus to five consecutive league titles before leaving the club in 2019.

He returned in 2021 and Juve re-signed Pogba on a free transfer the following year, but neither manager nor player have rekindled the success of their first stint at the club.

The 36-time Italian champions are currently second in Serie A, 12 points behind leaders Inter Milan, and have gone two seasons without a trophy under Allegri.

Pogba, who has made just one start and 11 substitute appearances in his second spell at Juve after being dogged by injuries, was tested randomly after their first match of the season on 20 August.

The positive result was confirmed by Italy's national anti-doping tribunal following testing of a second sample in October. The anti-doping prosecutor's office requested a four-year suspension.

Pogba said he believed the verdict was "incorrect" and he would appeal to the Court of Arbitration for Sport.

Allegri told a news conference he had sent the 2018 World Cup winner a message on Thursday after the announcement of the ban, which runs until August 2027, when Pogba will be 34.

But the Juventus coach said he would not comment further on the case while "there is a procedure under way".