Barca crashed to their first reverse of the campaign when they let slip a two-goal lead and were beaten 3-2 at Sociedad on Saturday and Atletico maintained their perfect home record with an efficient performance against Valencia-based Levante.
Diego Simeone's side, whose latest victory was soured by an injury to top scorer Radamel Falcao, have won all 10 of their league matches at their Calderon stadium and are second on 47 points from 20 games.
Barca have 55 points, while champions Real Madrid are 18 points behind their great rivals and 10 adrift of city neighbours Atletico in third ahead of their match at Valencia later on Sunday.
Adrian fired Atletico ahead in the 32nd minute when he connected with a Javi Manquillo centre at the far post and his first-time shot from a tight angle went into the net off Levante defender David Navarro.
Midfielder Koke curled in a second from the edge of the area on the hour and Atletico have now gone 10 games in all competitions without conceding a goal at home.
Colombia striker Falcao, who is coveted by several of Europe's richest clubs, had earlier pulled up clutching the back of his left leg and had to be replaced by Diego Costa.
The club said later on their Twitter feed he had damaged his hamstring but did not say how long he might be sidelined.
Atlético had 55.0% of possession.
Atlético had seven shots, four of which were accurate.
Diego Costa made the biggest impact of any Atlético substitute after coming on for Falcao in the 58th minute due to injury, as he assisted on Koke's goal.
The five attempts by Cristian Rodríguez were the most of any Atlético player.
Filipe Luis's 20 passes to Rodríguez were the most between any Atlético team-mates during the match.
Levante had 45.0% of the possession during the match.
Los Granotes had 10 shots, including two on target.
Míchel had two shots for Levante, more than any of his team-mates.