The 17-year-old has caught the eye with his performances in Ligue 1 and he has been involved in all 25 – starting 24 – league matches for his club to date this campaign, with Barcelona and Atletico Madrid among the clubs also linked.
Indeed, the teenager has featured in 36 matches for Rennes this campaign and he is said to have displayed the qualities to play a similar role for Madrid in the seasons to come.
The report adds that Casemiro has accumulated 3,120 minutes for Madrid this season across 35 matches and there is an awareness he could suffer from burnout in his career.
Los Blancos have tried other players in his position this season – including Fede Valverde – but there is no other specialist at the club.