That is according to Javier Ribalta, who is now a director at Zenit St Petersburg.
Ribalta spoke to Italian media after bringing Juventus midfielder Claudio Marchisio, 32, to Russian side Zenit on Tuesday.
Marchisio joined Zenit after leaving Juventus last month, following his fellow Italian to St Petersburg.
The midfielder had spent his entire club career at Juve – bar a loan spell at Empoli 11 years ago – but said goodbye to the Old Lady in mid-August.
Having snapped up Marchisio, Ribalta was asked about Juventus’ future transfer dealings.
The club have been linked with deals for Paul Pogba and PSG’s Adrien Rabiot.
But Ribalta reckons Marcelo is the man about to be captured.
“Marcelo. The other two seem impossible to me,” the former Manchester United scout told Tuttosport.
“When I heard that Marchisio had terminated his contract on August 17, I immediately called Claudio.
“There was no agent: I had known him well in my five years at Juventus.
“He seemed interested and intrigued by our project from the first moment, I honestly never feared he could choose a different club.”
Ribalta left United for Zenit this summer after just 13 months at Old Trafford.
He endured a mixed time at Old Trafford during which tensions between manager Jose Mourinho and executive-vice chairman Ed Woodward have threatened to spill over.
Ribalta had previously been head scout at Juve, where he helped sign top stars such as Pogba, Paulo Dybala, Kingsley Coman, Dani Alves and Alvaro Morata.
As for Juve, they are said to be interested in bringing Marcelo to the club in order to bolster Cristiano Ronaldo’s attacking threat.
Ronaldo thrived at Real Madrid with Marcelo playing behind the left-sided forward and Juve manager Max Allegri supposedly wants to reproduce that partnership in Turin.