Atletico Madrid and Barcelona showed the battle for the title would be a long, drawn-out affair after the Spanish co-leaders drew 0-0 in their first league meeting of the season on Saturday.
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 pair Diego Costa and Arda Turan 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.
"It was like a game of chess," Atletico coach Diego Simeone said. "The game reflected where these two teams are in the standings."
Atletico will remain encouraged about winning its 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 Simeone's all-black suit and jacket.
The hosts started more brightly as Turan's short cross along the goal-line was headed just over for the game's opening chance four minutes in.
The physical Diego Costa forced goalkeeper Victor Valdes into a save before awkward positioning kept him scoring from a headed-on corner in the 28th.
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. With Cesc Fabregas playing as a "false 9" Barcelona had trouble breaking through in attack.
"We expected a very strong, disciplined, and unrelenting opponent. They don't leave any open space in their area and it's very difficult to expose them," Barcelona midfielder Xavi Hernandez said. "We just couldn't create enough chances on goal. It was a very intense game."
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.
Andres Iniesta hurt his left knee and gave way to Messi 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. Alba and Daniel Alves made little impact in attack as the Barcelona fullbacks were cut off by Atletico's strikers.
Atletico looked set to break through in the 79th but Turan volleyed a looping ball straight at Valdes, moments before Courtois denied Messi's hard-taken shot from the left.
"I don't know what will happen between now and the last 19 rounds but I expect Atletico to stay in the fight," Barcelona coach Gerardo Martino said.
Also, Athletic Bilbao maintained its grip on fourth by demolishing Almeria 6-1 while Valencia's season-long slide continued with a 2-1 defeat at Celta Vigo.
Athletic enjoys a four-point cushion in fourth at the halfway point of the season, while Almeria sits three points above the drop zone. Celta moved three points clear of the relegation zone with the victory.
Daniel Carrico scored in the last minute as Sevilla rallied to draw 1-1 at Elche.