Raphael Varane only has a minor injury, according to Zinedine Zidane, who is hoping the centre-back will be fit to face Chelsea in midweek.
Varane was taken off at half-time against Osasuna on Saturday, with Madrid going on to win 2-0 thanks to late goals from Eder Militao and Casemiro.
The victory took Madrid back to within two points of LaLiga leaders Atletico Madrid, who beat Elche earlier on.
With Los Blancos facing fourth-placed Sevilla next week, and Barca hosting Atleti, the title race is firmly in the balance heading into the final few games of the campaign.
However, Varane's substitution was a cause for concern. Prior to facing Sevilla, Madrid will visit Stamford Bridge to play Chelsea on Wednesday, with their Champions League semi-final tie level at 1-1 after a tightly contested first leg.
Zidane is hopeful Varane's issue will not keep him out for long.
"I do not know, we have to wait," he told reporters. "He has told me that it is a small thing. I hope that is the case."
Madrid attempted 13 shots in the opening 45 minutes against Osasuna, more than they have managed in any other first half of a game this season in all competitions, though it took them until the 76th minute to find an opening – Isco's corner headed in by Militao for the centre-back's first LaLiga goal.
Casemiro's inadvertent finish subsequently put Madrid 2-0 up with 10 minutes remaining, and Zidane was pleased with the patience his team showed to make it 11 successive home wins against Osasuna in LaLiga – having last dropped points in this fixture when held 1-1 in December 2005.
"Happy with today's game, the three points. I am happy for the effort my players have made," Zidane added.
"In the first half we had four or five chances and we didn't score, it's a bit frustrating for them. At half-time I said [a goal] was going to arrive. With patience and with play.
"I was very happy for them, they are suffering there and when they score, you know it is a liberation."