Barcelona had to come from a goal down to rescue a 1-1 draw at mid-table Levante on Sunday, but remained joint top of the table after Atletico Madrid blew their chance to go top of La Liga.
Atletico had a chance to move on to 53 points from 20 matches with a win at home to Sevilla in the late kick-off, but drew 1-1 and stayed level with Barca, who dropped points for only the fourth time this season at Levante's Ciutat de Valencia stadium.
Real Madrid, who thrashed bottom side Real Betis 5-0 on Saturday, are third on 50 points, now just one point off the two leaders.
Barca lacked inspiration against a doggedly defensive Levante even with Lionel Messi, who returned last weekend after a two-month injury absence, back in the starting lineup.
Often vulnerable at defending set pieces, they fell behind in the 10th minute when Loukas Vyntra headed past goalkeeper Victor Valdes from an Andreas Ivanschitz corner.
Barca's equaliser also came from a corner when Gerard Pique nodded in nine minutes later but they struggled to create further chances before the break.
Messi drew a fine save from Levante keeper Keylor Navas in the 59th minute and Xavi's follow-up shot was brilliantly blocked on the line by home captain Juanfran.
Juanfran was again in the right place to divert another Messi effort out for a corner three minutes later and Navas leaped superbly to turn a curling effort from substitute Cristian Tello around the post five minutes from time.
"We tried and we did it well," Barcelona coach Gerardo Martino told a news conference.
"Down the wings, through the middle, trying to make the breakthrough," added the Argentine.
"We are coming away feeling sad because we were not able to get the victory. We know that this kind of match nine times out of 10 we would win."
Barca were unable to produce the scintillating form that helped them thump Levante 7-0 at the Nou Camp in August and they also play the Valencia-based club over two legs in the quarter-finals of the Copa del Rey this week and next.