The home side will enter the contest off the back of a 2-0 loss to Athletic Bilbao in the Basque derby, while Rayo recorded a 2-1 victory over Osasuna in their last La Liga match.
Match preview
Real Sociedad remain in fourth position in the table, picking up 51 points from their 29 matches, but they are only three points behind fifth-placed Real Betis in the battle to secure a top-four finish.
Villarreal are also involved in the race for fourth, sitting just four points off the final Champions League spot, and Real Sociedad have had a wobble at the worst possible time of the campaign, only winning twice in Spain's top flight since the middle of February.
Imanol Alguacil's side have managed to overcome Elche and Getafe in their last two games in front of their own supporters, but they have lost their last two away from home against Villarreal and Athletic.
The Basque outfit have a huge game away to Real Betis next Wednesday, and they must start to regain some consistency entering the final straight in order to hold onto fourth position in the table.
Alguacil's team recorded a 2-0 win over Rayo in the reverse match earlier this season, while they have not lost to the capital outfit in Spain's top flight since January 2015.
Rayo will enter this contest off the back of a 2-1 victory over Osasuna, which proved to be their first win in the league since the start of February.
Andoni Iraola's side have seen their European hopes fade in recent weeks, but they have still had an excellent campaign, collecting 40 points from 29 matches to sit eighth in the table.
Los Franjirrojos have never finished higher than eighth in Spain's top flight, so the club are chasing history this term, and they are only three points behind seventh-placed Athletic on the same number of games (29).
Rayo have been relatively impressive on their travels this season, picking up 17 points from 14 matches, although they have not managed to win away from home in the league since the end of January.
The capital outfit have two difficult games against Real Sociedad and Barcelona before ending the month away to basement side Elche, while May will begin with a home game against Real Valladolid.
Real Sociedad La Liga form:
D
D
W
L
W
L
Real Sociedad form (all competitions):
D
D
W
L
W
L
Rayo Vallecano La Liga form:
D
L
D
D
L
W
Team News
Real Sociedad will again be without the services of Sadiq Umar and Martin Merquelanz due to injuries, while Robin Le Normand is suspended following his booking against Athletic Bilbao.
Head coach Alguacil is expected to make a couple of changes from the side that took to the field for the first whistle of the Basque derby, with Alexander Sorloth likely to return in the final third.
Meanwhile, Le Normand's spot at the back should be taken by Aritz Elustondo, with Mikel Merino, David Silva, Martin Zubimendi and Brais Mendez continuing in midfield.
Rayo, meanwhile, will welcome Florian Lejeune back into their starting side, with the centre-back serving a suspension in the win over Osasuna last time out.
However, the visitors will now be without both Alejandro Catena and Alvaro Garcia, who both picked up bookings in the team's last match.
Lejeune should come straight back into the side as Catena's replacement, while Salvi is likely to benefit from Alvaro Garcia's absence to feature alongside Isi Palazon and Sergio Camello in the final third of the field.
Real Sociedad possible starting lineup:
Remiro; Gorosabel, Zubeldia, Elustondo, Munoz; Merino, D Silva, Zubimendi, Mendez; Sorloth, Oyarzabal
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Mumin, Lejeune, F Garcia; Comesana, Valentin; Palazon, Trejo, Salvi; Camello
We say: Real Sociedad 2-1 Rayo Vallecano
Real Sociedad are in desperate need of the points in their battle to secure a top-four finish, and we are backing the Basque outfit to return to winning ways here. Rayo are more than capable of picking up a positive result on Saturday but might ultimately fall just short against Alguacil's side.