The Portuguese suffered a minor knee injury in the midweek win over Borussia Dortmund but will no doubt be needed for a game against a side with a formidable home record.
Real Madrid's La Liga title chase takes it to Real Sociedad on Saturday, but trips to Anoeta have proved fruitless for many this season.
Carlo Ancelotti's men recovered from back-to-back league defeats with a 5-0 demolition of Rayo Vallecano last weekend, before cruising to a 3-0 win against Borussia Dortmund in the first-leg of their Champions League quarterfinal tie in midweek.
They sit third in the three-way battle for the title, three points behind leaders Atletico Madrid and two adrift of Barcelona, but Sociedad is a difficult nut to crack on home soil this season, having lost just two of 15 league fixtures in front of its own fans.
Barca and Athletic Bilbao are among those sides to come away from Anoeta empty-handed so far this season, as Sociedad continues to eye Champions League qualification for a second successive season.
Jagoba Arrasate's charges are six points short of fourth-placed Bilbao, with seven matches left to play, and will take confidence from their 3-3 draw against the men from the Spanish capital in this fixture last year.
Cristiano Ronaldo was booed by his own supporters during last week's win over Rayo, but showed few ill effects as he regained their backing by finding the net in his 100th Champions League appearance Wednesday.
The Portugal captain was, however, withdrawn by Ancelotti 10 minutes from time, although the Blancos boss has since moved to allay fears of a serious knee injury, calling the problem a "minor annoyance".
Midfielder Xabi Alonso praised Ronaldo for his discipline in coming off before the issue developed into something more serious.
"Cristiano did the right thing in coming off as a precaution, but I don't think he'll have any problems for Saturday," he told the club's official website. "I think he could progress well and be ready to play. He has a small niggle. It's not surprising that there are so many injuries. We have to be careful with the calendar because everything's very close together."
Alonso also stressed that the team would not favor the Champions League over La Liga, adding: "It's not a question of choosing; you have to fight for everything and we have a great opportunity in all competitions.
"In the Liga we are doing better than last year."
In addition to the slight question marks over the fitness of Ronaldo, Madrid is likely to have to do without the services of Marcelo once again after the fullback was confirmed to be suffering from a torn hamstring earlier this week.