However, Zidane has said he does not plan to strengthen in the January transfer window and he trusts his current squad, per beIN Sports.
This season has seen Los Blancos already lose three times in 17 games - Barca are unbeaten - which has been in stark contrast to a stellar 2017 which saw Madrid sweep up a record five trophies.
Having been held by Celta Vigo in the league and Numancia in the Copa del Rey in their last two games, Madrid face another tricky task at the weekend as they host sixth placed Villarreal in La Liga. "I have to try to get each one of them to give a little bit more".More news: Manila to impose gun ban for 2018 Black Nazarene feast
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"The club has had some negative results but that doesn't mean he's doing bad". It has never been able to overcome this big of a gap and win La Liga.
In the night's other early second leg tie, last season's runners-up Alaves downed third division Formentera 2-0 for a 5-1 aggregate win.
Real Madrid need to rediscover home comforts when they entertain Villarreal in the Santiago Bernabeu here on Saturday.
Zidane, who this week confirmed he has renewed his contract with Madrid until 2020, said he was not anxious about the team being jeered by fans at the Bernabeu, but made a plea for their support.
Reportedly asked whether he will sign a new deal with Chelsea, Hazard is said to have told the Mirror: "Yes. I think there are always up and downs throughout the season and I hope Real Madrid continue to fight for the goals they have this season".
Villarreal have the players to cause the hosts problems, but Zidane will demand a response from his side after a hard spell.