A superb solo strike provided Benzema’s landmark moment and put Madrid on the path to a commanding win that sent them top of Group G in Santiago Solari’s first European match at the helm.
The opener came after Sergio Ramos escaped punishment for an elbow on Milan Havel, but there was no stopping the visitors as Casemiro extended their lead in the 23rd minute.
Benzema doubled his tally and set up Gareth Bale in the space of 144 seconds towards the end of the first half, and Toni Kroos floated a beautiful 67th-minute chip home to wrap up the win and leave Plzen playing solely for third place.
Madrid’s injury-hit defence almost conceded in the ninth minute when Nacho Fernandez sent Patrik Hrosovsky’s cross against the bar.
Havel was left with a bloody nose after being caught by Ramos’ in a 14th-minute challenge, and the injury sustained by the Plzen midfielder eventually led to his first-half withdrawal.
Madrid soon asserted their superiority when Benzema was granted space to run into and he used it to slot his milestone strike between the legs of Ales Hruska in the 20th minute.
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