Real Madrid coach Zinedine Zidane said his team would "suffer" until the end after Saturday's last gasp 2-1 win at home to Valencia kept them on track for the title.
Zidane's team were ahead at the break thanks to Cristiano Ronaldo's 27th-minute header but found it difficult to put away an injury and suspension-hit Valencia side.
Karim Benzema struck a post early in the second half and Ronaldo saw a spot-kick saved by Diego Alves before ex-Madrid midfielder Dani Parejo curled a 25-yard free kick home to equalise with eight minutes left.
But left-back Marcelo cut inside from the wing to send a low right-footed shot past Alves and put his side three points clear, although Barcelona can return to the top should they win at Espanyol later on Saturday.
Real, who will also have a game in hand, have won seven La Liga games in the last 10 minutes and Zidane said: "After the Valencia goal we woke up again, and also the fans pushed the players on again. The game was different then.
"We know about this [the ability to win games late on], but I cannot explain why it happens. That is why football is so good -- it's exciting to win like that at the end."
Zidane said his players may have let their minds turn to Tuesday's Champions League semifinal first leg at home to Atletico Madrid.
"From my experience as a player, if you know that on Tuesday you have such an important game, you think you can just control the game maybe," he said.
"But these fans, in difficult moments, help us to get more energy at the end of the game."
Zidane said Madrid had not taken chances to "kill the game by scoring a second goal," adding: "In the end we will have this until the end, suffering until the end. This means we can still improve, nothing more."
But he rejected the idea that the much-rotated team that had won at Deportivo La Coruna showed he placed too much faith in the big names who returned against Valencia.
"This idea of A or B, I do not look at that," he said. "I just look at all the players."
Matchwinner Marcelo told BeIN SPORTS his team had dug deep and showed the desire needed to become champions.
"Today we have shown everyone who we are," he said. "With the fans pushing it is difficult to beat us here. I am happy for the goal, but even more for getting the points.
"We remain on our feet, and we will fight until the end. If we want to win the title we must win all the games we have left with patience and a lot of hard work."
