Real Madrid, who have a game in hand, can open a four-point gap if they beat Real Sociedad at the Santiago Bernabeu Stadium later today.
Sevilla can move three points in front of Barcelona if they win at Espanyol.
"This result wasn't in our plans, but we have the entire second half of the league still to play and we have to keep putting pressure on the teams ahead of us," Barcelona coach Luis Enrique said. "The most consistent team at the end will win. It feels like we won a point today."
Betis had a few good chances to put the game away, the best one came when striker Ruben Castro broke free toward the goal in the 80th but couldn't beat the goalkeeper from close range.
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"We had more chances but we couldn't capitalize on them," Alegria said. "It's never a bad result to draw against Barcelona, but after the game that we played today, it's a shame that we didn't get the victory."
The ball was nearly a meter (yard) inside the goal but the linesman ruled that it didn't go in. Another similar play happened just a few moments later, but on this occasion the ball appeared to be on the goal line when it was cleared by a defender.
Barcelona also appealed for a penalty after an apparent foul on Neymar.
The defending champion finally equalized after Messi stole the ball outside the box and immediately sent a perfect through ball to Suarez, who found the low right corner as the goalkeeper charged from the net.
Yesterday, fourth-place Atletico Madrid saw its title chances diminish after being held to a scoreless draw at promoted Alaves. Diego Simeone's team is seven points off the lead.