Atletico, Barca battle to draw
Both teams finished the first half of the season tied on 50 points after an exciting, back-and-forth showdown at Vicente Calderon Stadium yielded no winner.
Barcelona was troubled by Atletico striker Diego Costa throughout, while second-half substitute Lionel Messi enjoyed the visitors' best chances as the Barcelona forward headed wide before forcing goalkeeper Thibaut Courtois into a clutch stop in the 81st.
Neymar also came on in the second half for Barcelona but the Brazil striker made little impact as the teams played out their third straight draw following the summer Spanish Super Cup series.
Atletico will remain encouraged about winning their first title since 1996 and dislodging the Barcelona-Real Madrid monopoly that has been broken only by Deportivo La Coruna and Valencia since. Real Madrid travels to Espanyol on Sunday knowing a victory will move it to within three points of the leaders.
While Barcelona counted on its squad of regulars, Atletico's lineup was relatively unchanged down to coach Diego Simeone's all-black suit and jacket.
The hosts started more brightly behind Diego Costa as the Brazilian-born striker's short cross along the goal-line was headed just over for the game's opening chance four minutes in.
Barcelona braved Atletico's early surge and its choking pressure up the field with its passing game, with Pedro Rodriguez heading over goal in the 33rd before Courtois saved Gerard Pique's long, low shot.
Tension was building as the action moved end-to-end in the hard-fought, energetic match with Simeone warned by the referee to cool down just before the break.
Messi replaced Andres Iniesta to start the second half but it was Diego Costa who continued to prowl Barcelona's goal only to shoot wide in the 59th.
Messi perhaps showed some rust from a two-month injury layoff when he headed Jordi Alba's cross wide from the penalty spot at the other end.
Atletico looked set to break through in the 79th but Arda Turan volleyed a looping ball straight at Valdes, moments before Courtois denied Messi's hard-taken shot from the left.