The visitors are currently seventh in the table, one point behind sixth-placed Real Sociedad, while Rayo occupy 16th position, four points ahead of 18th-placed Cadiz.
Match preview
Rayo's form in the early stages of the campaign was excellent, but it has been a struggle for the capital side in recent months, and they have dropped dangerously close to the relegation zone.
Los Franjirrojos have won five, drawn 11 and lost 12 of their 28 league matches this season to collect 26 points, which has left them 16th in the table, just four points ahead of 18th-placed Cadiz with 10 games left.
Rayo will enter this match off the back of a 1-0 defeat to Alaves, and they have not been victorious in the league since a 2-0 success over Getafe at the start of January.
Inigo Perez was brought in as manager in the middle of last month, but he is still waiting for his first win, drawing two and losing two of his four matches at the helm.
The capital outfit have finished 12th and 11th in their two campaigns at this level since being promoted back to La Liga in 2021, but they are now facing a battle to retain their top-flight status.
Real Betis, meanwhile, are currently in a battle for sixth position, with Manuel Pellegrini's side sitting seventh, just one point behind sixth-placed Real Sociedad.
Los Verdiblancos recorded an impressive 3-1 win over Athletic Bilbao at the end of February, but it has not been a happy March thus far, losing their two games against Atletico Madrid and Villarreal.
Real Betis face a trip to Girona after the international break and will also tackle Valencia next month, with Los Che in the picture for a European spot, so it is set to be an important next few weeks for the team.
Pellegrini's side have struggled for consistency on their travels this season, only winning three of their 13 matches away from their own supporters, but Rayo have the second-worst home record, collecting only 10 points from 13 games, recording just one win in the process.
Real Betis are on a three-game winning run against Rayo, meanwhile, including a 1-0 victory in the reverse match earlier this season, and they have not lost to the capital side in Spain's top flight since April 2014.
Rayo Vallecano La Liga form:
L
L
D
L
D
L
Real Betis La Liga form:
D
W
D
W
L
L
Real Betis form (all competitions):
L
D
D
W
L
L
Team News
Rayo were missing Alvaro Garcia and Diego Mendez for their clash with Alaves last time out, and the pair are both expected to be unavailable for selection once again this weekend.
The capital side have no fresh injury concerns, but there could be a change at left-back for this match, with Pep Chavarria bidding to be involved from the first whistle.
Head coach Perez could also introduce Sergio Camello in the final third of the field, but Isi Palazon and Jorge de Frutos should retain their positions in the wide areas on Sunday.
As for Real Betis, Claudio Bravo, Aitor Ruibal, Hector Bellerin, Cedric Bakambu and Marc Bartra are out of the contest through injury, while Isco remains a doubt due to a hamstring problem.
The visitors will also be missing Ezequiel Avila due to the red card that he received in the 3-2 home defeat to Villarreal last time out.
German Pezzella is available again following a suspension, though, and he should return to the middle of the defence, while Ayoze Perez is expected to be the player to benefit from Avila's absence.
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Hernandez, Lejeune, Chavarria; U Lopez, Ciss; Palazon, Perez, De Frutos; Camello
Real Betis possible starting lineup:
Silva; Sabaly, Pezzella, Riad, Miranda; Rodriguez, Carvalho; Fornals, Fekir, Perez; Willian Jose
We say: Rayo Vallecano 0-1 Real Betis
Ten years have passed since Rayo managed to overcome Real Betis in Spain's top flight, and we are expecting that run to continue this weekend. The visitors need to bounce back to aid their top-six hopes, and we can see Pellegrini's side navigating their way to a narrow success on Sunday.