Raul's glancing header just before the break was all that separated the sides in a game with few sights of goal, though Iker Casillas pulled off a spectacular save to deny Angel Lafita before a late rally from Real at the end.
The champions made it five consecutive wins under Juande Ramos, and moved clear in second place with 41 points, 12 short of Barca after 20 games.
Barcelona swept aside Numancia 4-1 at the Nou Camp on Saturday.
Third-placed Sevilla and fourth-placed Valencia failed to keep the pressure on the top two as both slumped to defeats earlier in the day.
Sevilla were beaten 2-0 at home by Racing Santander, who played for nearly an hour with ten men, and Valencia were surprised 3-1 away by struggling Real Mallorca.
Racing's towering Serbian striker Nikola Zigic did the damage at the Sanchez Pizjuan, despite his team mate Oscar Serrano getting sent off in the 32nd minute.
Zigic's header at a freekick in the 24th was saved only for Cesar Navas to put away the rebound, and he muscled his way through to poke in Pedro Munitis's low freekick just after the re-start.
Mallorca dragged themselves off the foot of the table with a comprehensive demolition of Champions League hopefuls Valencia.
Mallorca, who last won a league game at the end of October, were inspired by midfielder Jurado who scored the opener, won the penalty for the second which Jose Luis Marti scored, and bagged the third just before the break.
Vicente pulled one back for the visitors but Mallorca were always the better side and they climbed to 18th.
Sevilla have 38 points, four ahead of Valencia who are kept above Villarreal on goal difference. Villarreal drew 1-1 at home against bottom club Osasuna on Saturday.
Atletico Madrid are sixth with 32 points after failing to make the most of Valencia's slip-up, drawing 1-1 at seventh-placed Malaga.
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