The win gave Real a 10-point lead on arch-rivals Barcelona and will be enough to secure the championship if Barca lose to Rayo Vallecano later later night.
Cristiano Ronaldo opened the scoring at the Bernabeu and Benzema added a brace after the interval to put Real within touching distance of a first La Liga title since 2008.
Real, who were eliminated from the Champions League after a semi-final defeat to Bayern Munich in midweek, thus took their record breaking haul of league goals for the season to 112.
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