Los Blancos announced on Friday that Bellingham had suffered an issue with his right leg during the morning training session, and the England international is now set to be out until the end of September.
Eduardo Camavinga is also absent until after next month's international break due to a knee problem, so 38-year-old Modric is expected to be introduced into the side against Real Valladolid.
Ferland Mendy will also be missing for Carlo Ancelotti's side due to the red card that he picked up in the latter stages of last weekend's 1-1 draw with Mallorca.
Fran Garcia should therefore earn a start, but it is otherwise expected to be the side that took to the field for the first whistle against Mallorca.
Rodrygo, Kylian Mbappe and Vinicius Junior should continue as the front three, while Federico Valverde and Aurelien Tchouameni will operate in the middle of midfield.
David Alaba is yet to recover from the serious knee injury that he suffered towards the end of last year, so it will again be Eder Militao and Antonio Rudiger in the middle of the Real Madrid defence.
Real Madrid possible starting lineup: Courtois; Carvajal, Militao, Rudiger, F Garcia; Valverde, Tchouameni, Modric; Rodrygo, Mbappe, Vinicius
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