City are favourites to sign the midfielder at the end of this season after his agent was spotted in Madrid a fortnight ago meeting with City officials at a local restaurant.
Don Balon says City boss Pep Guardiola wants to sign Isco - and a deal appears likely.
However, Ronaldo has urged Perez to use their interest to discuss bringing Bernardo Silva to Madrid. Ronaldo is a fan of his Portugal teammate and believes his game would better suit their system than Isco.
Indeed for Ronaldo, Isco's sale cannot come soon enough as the pair do not get along.