If Real Madrid decide to enter the race to sign Neymar from PSG then they'll have to use Casemiro as part of any deal, with the French champions keen on signing the midfielder.
On Monday night a report in Brazil confirmed that Barcelona were in talks with PSG to bring Neymar back to the Nou Camp with the Spanish champions reportedly offering €100 million plus three players.
Those talks being reported could open the way for others to bid for the Brazil forward and the French club have their eyes on another part exchange.
According to Spanish outlet MARCA, should Real Madrid try to sign Neymar then the French champions would ask for midfielder Casemiro as part of any deal.
Real have twice previously been interested in signing the former Barca man. When he moved from Santos to the Nou Camp Real also wanted to sign the forward.
Then when PSG paid €220 million for the 27-year-old it was rumoured that Los Blancos would also make a bid for him.
It has already been a big summer of spending at the Bernabeu with Eder Militao, Ferland Mendy, Eden Hazard, Rodrygo and Luka Jovic all moving to the Spanish capital.
They have also been linked with a big money move for Paul Pogba but if Neymar suddenly becomes available then they could be tempted to make a move for him.
The Parisians would want to recoup as close to the money they paid just two summers ago, when they smashed the previous transfer record, and exchange deals are the best way of bringing the cash element down.
Barca are believed to be offering Ousmane Dembele, Ivan Rakitic and Samuel Umtiti as part of their deal, although it could be several others as the three instead.
Casemiro has been a pivotal part of Real Madrid's success in the past but Marca reckon that his importance to Zinedine Zidane's team next season won't be as high.
PSG have had issues with a central midfielder ever since Thiago Motta decided to retire last summer and they signed Leandro Paredes last summer
Will Neymar leave the Parc des Princes this summer?