Having collected 56 points from 36 matches, Los Verdiblancos will head into the weekend in seventh place in La Liga, while Real Sociedad are sitting one point ahead in sixth position.
Match preview
Betis moved into sixth place with a 3-2 win over Almeria on matchday 35, but they dropped back to seventh following Thursday's frustrating 2-2 draw with Las Palmas.
Facing a side that had lost eight games on the bounce, Betis would have fancied their chances of beating Las Palmas, especially as they took the lead on two occasions thanks to a Mika Marmol own goal and an Ayoze Perez effort.
However, Los Verdiblancos conceded a couple of equalisers to drop two points and allow Real Sociedad to reclaim seventh spot ahead of the final two matchdays.
Despite missing out on a win, the result extended Betis' unbeaten run to six matches, leaving them five points clear of Villarreal and on the verge of securing European qualification for a fourth consecutive season.
As it stands, Betis are well set to clinch a Europa Conference League spot, but they know that if they beat Real Sociedad and Real Madrid they will secure a sixth-place finish and Europa League qualification.
Los Verdiblancos have fared reasonably well in recent meetings with La Real, having avoided defeat in each of their previous six head-to-head matches, although they have had to settle for goalless draws in the last two encounters.
Real Sociedad collected a narrow 1-0 victory in Thursday's home clash with Valencia to take advantage of Betis' draw against Las Palmas.
Andre Silva's third-minute effort proved enough to edge out Valencia and clinch a second straight home victory with a clean sheet.
As a result of that resolute display, Real Sociedad have now recorded 14 La Liga shutouts and has conceded just 37 goals in 36 matches, leaving them with the joint second-best defensive record alongside their Basque rivals Athletic Bilbao.
Imanol Alguacil's side will fall short of last season's fourth-place finish, but if they beat Betis they will be guaranteed to achieve a top-six finish for a sixth consecutive season.
Real Sociedad will head to Andalusia with the fourth-best away record in the top flight, having collected 27 points from their 18 road trips this season.
After failing to win on their last two trips to the Benito Villamarin, La Real will hope to claim their first away win over Betis since October 2020.
Real Betis La Liga form:
W
W
D
W
W
D
Real Sociedad La Liga form:
D
D
L
W
L
W
Team News
Betis' are unable to call upon their standout player of the season after it was confirmed that Isco sustained a leg injury in Thursday's clash with Las Palmas, ruling him out of the final two games and quashing his hopes of a potential call-up for Spain's Euro 2024 squad.
Argentine midfielder Guido Rodriguez was also forced off in midweek and will have to be assessed ahead of Sunday's contest.
Pellegrini is still having to cope without the services of Marc Bartra, Cedric Bakambu and Chimy Avila, while German Pezzella is a doubt after missing the last two matches.
Youssouf Sabaly, Juan Miranda, Jonny Cardoso and Willian Jose are all set to be recalled to the lineup, while there will also be a starting spot for Nabil Fekir.
As for the visitors, their treatment room features Aihen Munoz, Martin Merquelanz, Martin Zubimendi, Igor Zubeldia and Carlos Fernandez.
Atletico Madrid loanee Javi Galan remains a doubt for Sunday's contest after missing the last matches with a foot injury.
After making a number of changes in midweek, Alguacil could be tempted to recall Hamari Traore, Brais Mendez Sheraldo Becker and Mikel Oyarzabal.
Real Betis possible starting lineup:
Silva; Sabaly, Sokratis, Riad, Miranda; Cardoso, Roca; Fornals, Fekir, Perez; Willian Jose
Real Sociedad possible starting lineup:
Remiro; Traore, Le Normand, Pacheco, Tierney; Merino, Mendez, Turrientes, Merino; Kubo, Becker, Oyarzabal.