Karim Benzema scored the only goal of the game as Real Madrid extended their lead at the top of La Liga to seven points by beating Athletic Bilbao.
The France international scored his 17th goal of the season when he diverted home Luka Modric's wayward shot five minutes before half-time.
The visitors pressed late on but were unable to find an equaliser and remain eighth, without a win in six games.
Victory extended Real's advantage over defending champions Atletico Madrid.
And Carlo Ancelotti's side were dominant for long periods, having 62% possession and 17 shots on goal.
They made the breakthrough when Benzema turned home from 10 yards for his 12th league goal of the season after Modric skewed a shot into his path when Unai Simon parried Marco Asensio's effort.
Benzema has now scored 35 goals in 46 games in all competitions for Real in 2021, equalling his best goalscoring tally in a single calendar year for the club in 2019.
Mikel Vesga was twice denied by good Real blocks, while Yeray and Oier Zarraga both failed to hit the target with late efforts.