Captain Ramos injured his ankle in the final of the Spanish Supercopa last Sunday against Atletico in Saudi Arabia, in which he scored the winning penalty.
The defender took part in training with tape on his leg on Friday, but has been left out of Madrid's 19-man squad and will play no part against his former club.
Benzema missed the Supercopa altogether with bruising on his hamstring, but the French forward trained on Friday and is in line to replace Luka Jovic, himself recovering from a minor injury.
Gareth Bale was expected to be back from a minor illness which saw him miss the trip to Saudi Arabia, but is not included in the squad. Eden Hazard and Marco Asensio are both still sidelined and James Rodriguez has been left out by coach Zinedine Zidane.
Meanwhile, midfielder Fede Valverde is suspended after he was handed a one-match ban for his foul on Alvaro Morata against Atletico, which earned the Uruguayan a red card late in extra time in Jeddah.
Madrid are in second spot at the league's halfway stage, behind leaders Barcelona on goal difference alone. Sevilla are five points back in fourth, level with third-placed Atletico.
Argentine winger Lucas Ocampos is suspended for the visitors.
Real Madrid possible XI: Courtois, Carvajal, Varane, Militao, Mendy; Casemiro, Kroos, Modric; Isco; Rodrygo, Benzema
Sevilla possible XI: Vaclik; Navas, Carlos, Carrico, Escudero; Benega, Fernando, Jordan; Vazquez, De Jong, Munir