Real Madrid has opened up a 13-point gap at the top of LaLiga, after they beat Atletico Madrid 2-0 on Sunday.
Fit-again Karim Benzema gave Carlo Ancelotti’s men the lead in the 16th minute, volleying Vinicius Junior’s cross past Jan Oblak.
It was Benzema’s 13th league goal of the season, as he continues to lead Real’s title march.
Marco Asensio then finished off a ruthless counter-attack in the 57th minute, to seal a 10th consecutive win for Los Blancos in all competitions.
The victory means Atletico has now gone 11 LaLiga derbies without a win, a run stretching back to 2016.
Barcelona is now 18 points adrift after they were earlier held to a 2-2 draw away at Osasuna.
Sevilla, who last won the Spanish title in 1946, is the closest challenger, eight points back, and having played a game fewer.