Juventus great Alessandro Del Piero expects his former club to make a huge statement in the transfer window following the shock sale of Leonardo Bonucci to AC Milan.

Bonucci joined Juve's ambitious Serie A rival in a deal worth €42million amid reports of a breakdown in relations between the Italy centre-back and manager Massimiliano Allegri.

The pair clashed during Juventus's Serie A win at Palermo last season, with Bonucci dropped for the subsequent trip to Porto, and the defender was forced to deny allegations of a bust-up at half-time during the UEFA Champions League final defeat to Real Madrid in Cardiff.

Del Piero was no stranger to a dressing room of big personalities during his 19-year association with the Old Lady and suggested relations with a player of Bonucci's quality must have been beyond repair.

"It's a transfer that surprised me," he told Gazzetta dello Sport. "We need to see what really happened to come to this conclusion.

"Juve has some very precise rules. In my 19 years there I watched behaviour by some players who were sanctioned with heavy fines.

"Evidently in this case we came to a situation that could no longer be recomposed."

Douglas Costa's arrival on loan from Bayern Munich gave a timely boost to Allegri's squad as it chases a seventh consecutive Serie A title but Del Piero feels there is something more seismic in the pipeline.

"Now I expect a very important shot by Juve - the purchase of a player who has not yet been talked about," he said.