Real Madrid manager Zinedine Zidane was relieved to see his side edge past Real Valladolid 1-0 to move to the top of the La Liga table.
It took a late and rare strike from defender Nacho to break the deadlock after a disciplined defensive display from the hosts, who could have snatched a point at the end when Sergi Guardiola was denied by an offside flag.
Madrid midfielder Casemiro also had a goal ruled out by VAR in the first half but Zidane's men did enough as they extended their unbeaten run to 12 games.
"They're three important points against a team that never gave up," Zidane said.
"We knew that before the match and we played better in the second half.
"We went into it with a new dynamic. We were better in possession of the ball and with the rhythm of the game.
"We picked up three important points today."
Spain international Nacho was handed his fourth league start of the season only because usual right-back Dani Carvajal was suspended but he proved the difference in a tight encounter by heading home a Toni Kroos cross in the 78th minute.
Real, who have not won the title since 2017, lead the standings on 46 points after 21 games. Barca, who lost 2-0 at Valencia on Saturday in their first defeat under new coach Quique Setien, are second on 43 while Sevilla are third with 38.
Nacho raced straight over to the visiting dugout to embrace coach Zinedine Zidane after scoring his first league goal in over two years as Real finally broke the deadlock after struggling to break down the hosts' deep-lying defence.
Zidane revealed after the game that his instructions to Nacho had played a part in the goal.
"Just before he scored I told him to attack the near post. He's a defender who doesn't score many goals so I'm delighted for him," said the French coach.
"It was a very difficult match against a team who had only lost one game at home and who play very well. It was vital that we won but being top of the table doesn't change anything for us, we just have to keep doing what we're doing well."
Real Madrid captain Sergio Ramos said: "Nacho sums up the unity of this team and that any player can come in and make a difference regardless of how many minutes they have played this season. The whole squad is so happy for him.
"It's never easy to play away from home and we knew that Valladolid would play their usual system and defend very well and close us down and we had to work very hard to open them up."
