Second-placed Osasuna's club record ninth home victory in a row gave them 38 points from 17 matches.
Champions Barcelona chalked up their 13th consecutive win in all competitions when they beat Celta Vigo 2-0 on Tuesday.
Valencia, on 32 points, overcame Real Mallorca 3-0 on Wednesday. Fourth-placed Villarreal have 30 points while strife-torn Real Madrid are fifth after their 2-1 defeat at home to Racing Santander the same night.
There was little to separate Osasuna and Atletico in the opening minutes at a freezing El Sadar.
The Navarrans suffered an early setback when striker Savo Milosevic went off injured after a quarter of an hour but his replacement Bernardo Romeo went on to play a decisive role in the home side's victory.
The game sparked into life after 26 minutes when Atletico snatched the lead after a speculative shot from Gabi.
OFF GUARD
The midfielder's shot caught keeper Ricardo off guard as it skidded off the icy pitch, hit the post and fell into the path of Martin Petrov who fired high into the net.
It took Osasuna three minutes to equalise, in-form midfielder Raul Garcia curling a shot past Atletico's stand-in keeper Roberto Jimenez after good work from Argentine striker Romeo.
Five minutes later they were in front, this time Romeo providing the finishing touch to a devastating counter-attack by dinking the ball over Jimenez after French winger Ludovic Delporte had curled a pass in from the left.
Osasuna outplayed Atletico for the remainder of the game and man-of-the-match Romeo struck the woodwork twice after the break.
Toothless Atletico, who have now gone eight games without a win, were unable to manufacture a single scoring chance in the second half as the pressure piled on beleaguered coach Carlos Bianchi.
