The home side are currently sixth in the La Liga table, six points behind fifth-placed Athletic Bilbao, while Rayo occupy 13th position, eight points ahead of the relegation zone.
Match preview
Real Sociedad booked their spot in the semi-finals of the Copa del Rey courtesy of a 2-1 success over Celta Vigo on Tuesday evening, and the result made it three straight victories in all competitions.
Imanol Alguacil's side also beat Celta in the league last weekend, recording a 1-0 victory, but they have ground to make up in terms of the top-four race this season, with the Basque outfit currently sitting sixth in the table, six points behind both fifth-placed Athletic and fourth-placed Atletico Madrid.
Real Sociedad are fighting on three fronts this season, as they are also in the knockout stage of the Champions League and will head to Paris Saint-Germain for the first leg of their last-16 tie on February 14.
The White and Blues have only lost four times in the league this term, but they have drawn eight, with four of those stalemates coming in front of their own supporters.
La Real, who finished fourth in Spain's top flight last season, are unbeaten against Rayo in La Liga since January 2015, but the points were shared in a 2-2 draw when they locked horns in Madrid earlier this term.
Rayo will certainly be the fresher of the two teams entering this match, with Francisco's side not in action since suffering a 2-0 home defeat to Las Palmas last weekend.
The capital team beat Getafe 2-0 in the league on January 2, but they have won just one of their last 10 matches in Spain's top flight, which has seen them drop out of the top half of the table.
Los Franjirrojos are currently 13th, boasting 23 points from their 20 league matches this season courtesy of a record of five wins, eight draws and seven defeats.
Rayo are only three points behind 10th-placed Getafe and eight clear of the relegation zone, so they should be looking up the division rather than down despite their struggles for wins.
The Vallecas outfit actually have the sixth-best away record in the division this season, picking up more points on their travels (15) than in front of their own supporters (eight).
Real Sociedad La Liga form:
W
D
D
D
L
W
Real Sociedad form (all competitions):
D
W
L
W
W
W
Rayo Vallecano La Liga form:
L
D
L
L
W
L
Rayo Vallecano form (all competitions):
L
L
W
W
L
L
Team News
Real Sociedad will be missing Carlos Fernandez, Alvaro Odriozola and Martin Merquelanz for this weekend's contest through injury, while Ander Barrenetxea and Kieran Tierney are fitness doubts.
The home side will also be without Mikel Merino due to suspension, while Hamari Traore and Takefusa Kubo remain in action at the Africa Cup of Nations and Asian Cup respectively.
Sheraldo Becker scored his first goal for the club against Celta in the Copa del Rey, and the January arrival could now be given the nod in the final third of the field alongside Mikel Oyarzabal.
As for Rayo, Pathe Ciss and Bebe remain unavailable for selection, with the pair representing Senegal and Cape Verde respectively at the Africa Cup of Nations.
The hosts will also be unable to call upon Alvaro Garcia, who was sent off in the latter stages of the team's home defeat to Las Palmas last weekend.
Garcia's absence is expected to open the door for Jorge de Frutos to come into the starting side, but Sergio Camello should retain his spot at centre-forward despite competition from the likes of Raul de Tomas and Radamel Falcao.
Real Sociedad possible starting lineup:
Remiro; Aramburu, Zubeldia, Le Normand, Pacheco, Munoz; Mendez, Zubimendi, Turrientes; Oyarzabal, Becker
Rayo Vallecano possible starting lineup:
Dimitrievski; Balliu, Aridane, Lejeune, Espino; Palazon, Lopez, Valentin, De Frutos; Camello, Trejo
We say: Real Sociedad 2-1 Rayo Vallecano
Five of the last nine La Liga meetings between these two sides have finished level, and it would certainly not be a shock to see the points shared on Saturday. Real Sociedad will again be missing some important players, but we are expecting the Basque outfit to navigate their way to an important three points.