Real Madrid beat Group G rivals Viktoria Plzen, but it was another unconvincing display by the European champions, whose coach Julen Lopetegui reportedly faces losing his job.
The Spanish giants came into the game on the back of four defeats in five games in all competitions.
Karim Benzema's header gave Real the lead in the 11th minute - his 57th goal in the Champions League.
Marcelo dinked home a second before Patrik Hrosovsky drove in for Plzen.
Asked afterwards whether he would be in charge for the weekend's El Clasico at Barcelona, the Real coach said: "This question is not for me. We are thinking about preparing for Sunday's game which is very important, and we will go with great ambition."
Real were close to scoring early in the match when veteran defender Sergio Ramos nodded over and then against the post.
Benzema, however, hit the target with his header as he converted Lucas Vazquez's chip to the far post.
Brazil full-back Marcelo then doubled Real's advantage with a chipped finish in the 55th minute after Gareth Bale's delicate pass had sent him clear.
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Czech side Plzen impressed at the Bernabeu. Milan Petrzela had a shot blocked by the thigh of Keylor Navas and then fired over from close range, while David Limbersky chipped wide.
They eventually scored 11 minutes from time when Hrosovsky fired into Navas' left-hand corner.
Source: BBC