Madrid was without Gareth Bale who was injured in Madrid’s Champions League against Sporting Lisbon.
But the European champions looked in control when Ronaldo scored twice in the first 18 minutes.
His opener was a penalty and his second was a header from Nacho’s cross – his eighth La Liga goal in four games.
But Carlos Carmona pulled one back and Duje Cop missed a penalty for the visitors with 13 minutes left.
The Croatia international, who appeared to check his pulse just before taking the kick, fired high and wide after Nacho was penalised for fouling Victor Rodriguez.
Sevilla can cut unbeaten Real’s lead to six points when they host Valencia at 19:45 GMT, while champions Barcelona can take it back down to four points on Sunday at Real Sociedad (19:45 GMT).
Ronaldo’s double takes him up to 10 La Liga goals for the season, two above Barcelona team-mates Lionel Messi and Luis Suarez in the golden boot race.
