Gareth Bale will be assessed by Real Madrid's medical staff on 24 April after the Welsh forward suffered a calf injury in the club's defeat against Barcelona at the Santiago Bernabeu.
Bale lasted only 38 minutes on his comeback from a calf injury picked up in the first leg of Madrid's Champions League game against Bayern Munich on 12 April.
He was replaced by Marco Asensio, with the home side going on to lose the game 3-2.
Madrid manager Zinedine Zidane insisted in his post-match press conference that he had no regrets over his decision to play Bale from the start against Barcelona.
"He said he was fine and eager to play. I don't regret it," the Frenchman told Real's official website.
"I'm disappointed for him because he wanted to play and this is something we can't control.
"Tomorrow we'll have a look and see what injury he has and I hope he'll not be out long."
Lionel Messi capped a sparkling performance with his 500th goal in Barcelona colours in the 92nd minute at the Bernabeu to breathe life back into the Catalan club's La Liga title challenge.
Casemiro and substitute James Rodriguez scored for Madrid, who had their captain Sergio Ramos sent off for a wild lunge at Messi in the 77th minute.
"The referee has decided to show Sergio a red card and we have to accept it. I've got nothing to be angry with my players about," Zidane added.
"I'm not going to blame my players. We always try and win the game and we just didn't manage it today.
"We've lost three points and we're disappointed because over the course of the game we didn't deserve to lose."
Barcelona's victory moved them to the top of the La Liga table by virtue of their superior head-to-head record against Madrid, although the capital club have a game in hand.
Real's next league assignment sees them taking on Deportivo La Coruna at the Riazor on 26 April.