The Blaugrana lost 2-0 to Valencia on Saturday, and Real took full advantage by beating Real Valladolid 1-0 on Sunday to move to the head of the table for the first time in three months:
Nacho was the unlikely goalscorer for Los Blancos at the Estadio Jose Zorrilla. He headed home Toni Kroos' cross in the 78th minute to wrap up all three points.
In the wake of the victory, Zidane said there is still a long way to go in the 2019-20 season, per Stephen Creek of Goal:
"For us, nothing changes. We are happy with the victory, the work done having fought until the end, but nothing changes. There are 17 games left and we will continue fighting until the end.
"I don't want to talk about being champions because there is still a lot left to play. It changes nothing to be leaders, they are three important points but nothing more. There are a lot of league games left and it will be difficult for all teams, including us."
Real have lost just once in 21 league games this season: October's 1-0 reverse to Mallorca.
Sunday's win over Valladolid was their third victory in succession, and Zidane's side are looking ominously effective at the moment.
They are not firing on all cylinders, but defensively they look robust, with Thibaut Courtois having kept clean sheets in four of Real's last five league games:
Barcelona, meanwhile, were ineffective in their 2-0 defeat to Los Che. New manager Quique Setien is clearly having an impact on the Blaugrana, but his methods are yet to take a positive hold:
Barca's decision to make a midseason change of manager and jettison Ernesto Valverde could have a huge bearing on the title race if the Catalans do not find their form quickly under Setien.
Valverde led the Camp Nou giants to successive league title victories in 2017-18 and 2018-19, but Real are now in the box seat in 2019-20.
Real's next league match is against Atletico Madrid at the Santiago Bernabeu on Saturday.
A derby is always a dangerous game, but Atleti are in poor form at the moment.
In their last two La Liga games they have lost to Eibar and drawn 0-0 at home with bottom-of-the-table Leganes.
Meanwhile, last week Diego Simeone's side were knocked out of the Copa del Rey by third-tier Cultural Leonesa.