Ndidi, 24, has been a key player for the Foxes since his arrival from Genk in January 2017, making 193 appearances in all competitions, including 17 outings during the 2021-22 campaign.
Manchester United have previously been credited with an interest in the Nigeria international, who has a contract at the King Power Stadium until June 2024.
However, according to El Nacional, Real Madrid are the favourites to sign the midfielder amid suggestions that he is keen to leave the Foxes due to their struggles during the 2021-22 campaign.
The report claims that Los Blancos are looking for a long-term replacement for Casemiro, who could be allowed to join Chelsea for the right price during next summer's transfer window.
Real Madrid boss Carlo Ancelotti is believed to be a keen admirer of Ndidi, having watched the Nigerian on a regular basis during his time in charge of Everton. body check tags ::