Goal understands that Juventus are keeping a close eye on proceedings and are ready to swoop if Inter fail to complete a transfer for the 23-year-old.
The deal that Inter have struck means that they must stump up the money for the Portuguese right-back by May 31, which poses them problems as that means it falls under the budget of the current campaign, potentially leaving the door open for the Serie A champions to make a move.
Juve continue to enjoy a strong relationship with Valencia, having previously done business over Simone Zaza and Neto, which could tip the balance of any deal in their favour.
The full-back positions are likely to need refreshing at Juventus Stadium this summer, with Kwadwo Asamoah and Stephan Lichtsteiner set to depart, while Alex Sandro is ready to consider a move if no new deal in Turin is quickly settled.
Inter, meanwhile, are determined to keep hold of Cancelo, who has played an increasingly large role in their first-team squad this season, starting 10 Serie A matches and playing close to 1000 minutes.