For the third successive round, Madrid had been provisionally knocked off the summit by second-placed Barca winning 24 hours previously, but the capital club responded again with a hard-fought 2-0 victory over lowly Racing.
It was far from comfortable for Madrid, but Ronaldo's successful 24th-minute penalty after the Portugal international had been brought down in the area put the visitors on course and Higuain sealed the win 14 minutes from time.
Real defender Raul Albiol remarked afterwards: "We knew that this was a very difficult venue.
"They also have a lot to play for and we knew it was a game in which the important thing was to win and go level on points with Barcelona. They were going well but with the first goal they couldn't ever relax. After the second goal we played with a greater calm."
Real coach Manuel Pellegrini said: "It's important to win and we did. We had left our strength and a clean sheet. We were not brilliant on the offensive, but we had more chances. Overall I am satisfied with the strength of the team.
"Now we musty look to the match versus Barcelona. Both sides arrive at the match at the right time, having recorded many victories. We need to recover the points we lost at the Camp Nou, and I am sure we can win."