Madrid closed the gap on their title rivals to three points last weekend thanks to a hard-fought 1-0 win away at Espanyol, while Atleti and Barça played out a 0-0 draw at the Vicente Calderon.
All three sides are still competing on three fronts as they progressed into the quarter-finals of the Spanish Copa del Rey in midweek ahead of a return to UEFA Champions League action next month.
Despite a run of good results, Madrid's performances have failed to convince in recent weeks. However, coach Carlo Ancelotti has hailed his side's competitive spirit to keep themselves in the title race.
"Now the most difficult part of the season comes because all the matches are important," Ancelotti said. "We don't always play fantastic football. We have a lot of games right now and to always play well isn't easy.
"But the team is concentrated, working very hard and is hungry to achieve things in the future."
A win for Real would mean they would move joint top for the first time since mid-September and Los Blancos will be heavy favourites against a Betis side rooted to the foot of the table and without a win in the league 12 games.
Barcelona are in action on Sunday as they travel to Levante where Lionel Messi is expected to start.
Messi scored twice in his first start since a two-month layoff due to a hamstring injury in the Copa del Rey win at Getafe on Thursday. However, the Argentinian will again not be able to link up with Neymar after the Brazilian suffered a sprained right ankle against Getafe.
Barça boss Gerardo Martino once again praised the work done by the likes of Alexis Sanchez, Pedro Rodriguez and Cesc Fabregas in his star strike duo's absence, but admitted Neymar and Messi will be key to his side's success in the second half of the season.
"It is clear that the extent to which Neymar and Messi's participation is continuous then we will have a better chance (to win things)," Martino said. "But, the results have borne up well in their absence."
"You plan the objectives for what happens at the end of the season and it is clear that Barça have to win a title because that is what they have done year after year."
Atletico are the last of the title contenders to take the field this weekend as they host an in-form Sevilla side who have moved into contention for the fourth Champions League place with a seven-game unbeaten run.
And midfielder Tiago is confident that his side can stave off tiredness to continue fighting on three fronts until the end of the campaign.
"We are going to try and we think that we can. We have a very good group of players and everyone will get their chance," he told the club's official website. "We need everyone to be at their best because it is not easy to keep competing in two games a week. Until now we have responded well and hopefully we can continue to do so."