Unbeaten since Immanol Alguacil became head coach on March 19, Sociedad climb to 43 points and sit 11th in the La Liga table, reports EFE news agency.
Atletico, meanwhile, remain at 71 points and will be looking anxiously over their shoulder at cross-town rivals Real Madrid, who have 68.
Neither side was dominant in the opening minutes at the Anoeta Stadium here on Thursday and neither goalkeeper was tested until the 20th minute, when Gero Rulli easily handled an effort from Atletico's Diego Godin.
The picture changed dramatically just seven minutes later as Adnan Januzaj penetrated the Atletico defence and got the ball to Willian Jose, who beat keeper Jan Oblak with a low shot to put the hosts ahead 1-0 and lift his season goal total to 14.
Januzaj nearly made it 2-0 right before the break with a strike that grazed the outside of the post.
The Colchoneros started the second half aggressively and became more effective on attack with the addition of subs Fernando Torres and Vitolo.
Atletico's best opportunity came on a free kick, but Sime Vrsaljko's header went wide and the initiative shifted back to Sociedad for the final quarter of the match.
Willian Jose missed a sure goal in the 73rd minute and Juanmi squandered a chance in the 78th before making good seconds later to put the home side ahead 2-0.
Juanmi headed into an open net in the final minute to complete the 3-0 rout.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
