Real needed a 77th minute goal from Benzema to win at Champions League newcomer Ludogorets, after Ronaldo missed one penalty before making amends with a second spot kick.
Ludogorets will look to match the stunning giant-killing exploits of compatriots CSKA Sofia when they make their Champions League home debut against holders Real Madrid.
Ronaldo scored in his sixth straight game to help Real Madrid win 2-0 at Villarreal in the Spanish league on Saturday.
Real Madrid will face a tougher test when they visit Villarreal on Saturday. Villarreal have lost only once, 1-0 to Barcelona, this season.
Ronaldo struck four times and Gareth Bale also got his name on the score sheet as Real Madrid thrashed Elche 5-1.
Real lost two La Liga matches in a row, before bouncing back with a 5-1 win against FC Basel in the Champions League last week.
Champions League kicked off previous week with first set of group matches and straightaway we witnessed thrilling action, drama and scintillating performances.
Cristiano Ronaldo struck a hat-trick as Real Madrid produced a stunning 8-2 demolition of Deportivo La Coruna in La Liga.
Varene arrived at Real Madrid from Lens in the summer of 2011 for 10 million euros and broke into the first team at the end of the 2011-12 campaign.
Real Madrid finally got their act together in the Champions League, and now it's time to keep the momentum rolling into the domestic competition following a disappointing start.
Bayern certainly had the better of City throughout their clash, although they needed a 90th minute goal from Boateng to win that Group E opener of Champions League .