The home side are currently fourth in Spain's top flight, boasting 22 points from their opening 11 matches of the season, while Real Betis sit fifth, two points behind their opponents this weekend.
Match preview
Real Sociedad's form over the last six weeks has been extraordinary, winning nine of their last 10 matches in all competitions, which has included five victories in Spain's top flight.
Imanol Alguacil's side have won seven, drawn one and lost three of their 11 La Liga matches this season to collect 22 points, which has left them in fourth position in the table, just one point behind third-placed Atletico Madrid heading into the next set of fixtures.
Real Sociedad were beaten 1-0 by Real Valladolid in the league last time out, though, so they will be bidding to return to winning ways in Sunday evening's contest with fellow top-four hopefuls Real Betis.
The Basque outfit were in Europa League action away to Omonia on Thursday evening and recorded a 2-0 victory to make it five wins from their five Group E games; Alguacil's side will top the group, and secure an automatic spot in the last-16 stage of the competition, providing that they do not suffer a two-goal defeat to Manchester United on home soil next Thursday.
Real Sociedad have not actually beaten Real Betis in the league since October 2020, while they have not been victorious against the Green and Whites at home since October 2019, although two of the last three meetings between the two sides have finished all square.
Real Betis, meanwhile, were also in Europa League action on Thursday evening, recording a 1-0 victory over Ludogorets, with Nabil Fekir scoring the only goal of the contest early in the second period.
Manuel Pellegrini's side have already secured first spot in Group C, with the team certain of a position in the knockout round of the competition, as they sit six points clear of second-placed Ludogorets.
Real Betis have only been victorious in one of their last four in the league, though, which was a 3-1 success over Almeria on October 16. Since then, they have drawn away to Cadiz and lost at home to Atletico Madrid, with the results leaving them in fifth spot in the table on 20 points.
The Green and Whites have finished sixth and fifth in their last two La Liga campaigns, but it does appear that fourth will be open in the league this season, as Sevilla are currently struggling.
El Glorioso recorded a 4-0 victory over Real Sociedad in Seville last season, while the reverse fixture finished goalless, and it will be fascinating to see what occurs this weekend between two of the best sides in Spain's top flight.
Real Sociedad La Liga form:
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Real Sociedad form (all competitions):
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Real Betis La Liga form:
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Real Betis form (all competitions):
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Team News
Real Sociedad will again be missing Mohamed Ali Cho, Umar Sadiq, Martin Merquelanz, Aihen Munoz and Mikel Oyarzabal through injury, while Alex Sola remains a doubt due to a knee problem.
There will be changes to the side that started against Omonia on Thursday, with Brais Mendez, Martin Zubimendi, Robin Le Normand and Andoni Gorosabel among those set to return.
Takefusa Kubo and Alexander Sorloth are expected to feature as the front two, with David Silva operating in the number 10 position for the in-form hosts.
As for Real Betis, Victor Camarasa and Juanmi remain on the sidelines through injury, but the squad will be boosted by the return of Sergio Canales from suspension.
Joaquin is expected to be missing due to the issue that he picked up in the first half of the clash with Ludogorets, and there will be a number of changes to the side that started on Thursday.
Fekir, Alex Moreno, Borja Iglesias, Rui Silva and German Pezzella will be among those to return, but Luiz Henrique could miss out, with Canales, Fekir and Rodri potentially playing behind Iglesias in attack.
Real Sociedad possible starting lineup:
Remiro; Gorosabel, Elustondo, Le Normand, Rico; Mendez, Zubimendi, Merino; D Silva; Sorloth, Kubo
Real Betis possible starting lineup:
Silva; Sabaly, Felipe, Pezzella, Moreno; Rodriguez, Carvalho; Canales, Fekir, Rodri; Iglesias
We say: Real Sociedad 1-1 Real Betis
This is a really difficult match to call, especially as both sides were in Europa League action on Thursday night. There is not much to choose between them in terms of quality, and despite Real Sociedad's excellent form of late, we are backing Real Betis to secure a share of the spoils in this match.