Bale is out with a calf problem and his fellow first-choice forwards will also not make the trip after being rested by head coach Zinedine Zidane.
Ronaldo earned his manager's praise Friday for hitting the century mark in goals scored in European competition, with Zinedine Zidane hailing his attacker's excellent form.
However, Ronaldo will have to wait to continue his fine form until the second leg against Bayern at the Bernabeu on Tuesday.
In addition to Ronaldo, Benzema and Bale, goalkeeper Keylor Navas has also been left out of Madrid's squad for the Sporting game while full-back Dani Carvajal was already ruled out with suspension, and Raphael Varane and Pepe are out through injury.
Castilla player Alvaro Tejero has been called up to make up the numbers in Madrid's 18-man squad and Fabio Coentrao could make only his second league appearance of the season.
The possibility of the full-back making a rare outing was talked up by Zidane in his pre-match media conference earlier on Friday.
Madrid are three points clear of Barca at the top of the table with a game in hand. Luis Enrique's men are also in action on Saturday with a home match against Real Sociedad.
The two teams meet in El Clasico next Sunday after Madrid have hosted Bayern on Tuesday. Zidane's side hold a 2-1 lead in the Champions League quarter-final tie.
Real Madrid squad to play Sporting: Casilla, Yanez, Ramos, Nacho, Marcelo, Coentrao, Danilo, Tejero, Kroos, James, Casemiro, Kovacic, Modrid, Asensio, Isco, Vazquez, Mariano, Morata.