Real Madrid 'are seeking assurances' from Paris Saint-Germain over Neymar's injury-prone feet before pressing ahead to sign him this summer.
Spanish publication MARCA report that Real have gathered vast information on Neymar's injury history and they 'acknowledge his fragility' over the course of a season.
But while the club are keen to prize the £198million star out of Paris, it appears further guarantees are needed before the club consider a world-record investment to get him.
Neymar missed the entirety of Brazil's Copa America success in the summer after picking up a leg injury in a pre-tournament match against Qatar.
He has returned to fitness now, training with his team-mates but continues to be of interest to both Real Madrid and Barcelona before the European transfer window closes on September 2.
Reports in Spain have detailed that the fitness issue is the main talking point between the two clubs after Real sent a delegation to Paris to 'open negotiations' over a deal, trying to steal a march on rivals Barcelona.