When these two sides last met, it was the first game week of the season and optimism was high, with the game eventually ending 1-1. With just two games left of the La Liga campaign, 25 points now separate the two sides, with Valladolid pursuing top-flight survival and La Real hoping to secure European football.
La Real's season has somewhat plateaued in recent months following the team's mid-season drop-off and poor run in the Europa League.
The fact that Imanol Alguacil's side were very much in the title race in November suddenly feels a very long time ago.
But La Real have fought a strong campaign, and they have picked up silverware along the way too.
However, recent league performances have been a mixed bag, with La Real losing three and winning three of their last six league games.
Against Valladolid, Alguacil's side come up against an entirely different outfit, but one which will be desperate for all three points.
Valladolid have largely blown hot and cold this season, but it will come as no surprise to neutrals that the team are now flirting with relegation.
Currently 18th in the standings, with 31 points, Sergio's men do not realistically have to win this tie, but positive results for the teams around them would be a nightmare scenario for Valladolid.
Los Pucelanos have lost two of their last six league outings, drawing four in the process.
Sergio will no doubt be concerned that his side have taken a dip in recent weeks, right before the going gets really tough.
It will take something special for Valladolid to come away with the points this weekend.
The biggest loss for La Real ahead of this fixture is midfield maestro Mikel Merino, who remains sidelined due to injury.
Sergio is still expected to be without star-man Fabian Orellana, who has scored six goals and provided two assists this season.
Another absentee for Valladolid is defender Raul Garcia, who is out with a knee injury.
Real Sociedad possible starting lineup:
Alex Remiro; Zaldua, Elustondo, Sagnan, Monreal; Guridi, Zubimendi, Portu, Oyarzabal, Barrenetxea; Isak
Real Valladolid possible starting lineup:
Roberto; Janko, Bruno, Yamiq, Nacho; Fernandez, Plano, Fede, Mesa, Villa; Weissman
We say: Real Sociedad 2-1 Real Valladolid
As the tussle at the foot of the table looks set to come to a head, Valladolid look like a side who could be on the way out. We think La Real will comfortably win this fixture, with Isak picking up a goal or two.