Gareth Bale will miss Real Madrid's trip to Sporting Gijon on Saturday and faces a race against time to be fit for Real's Champions League quarter-final second leg against Bayern Munich on Tuesday.
Bale had to be replaced for the final half hour of Madrid's 2-1 win in Munich on Wednesday after aggravating an ankle injury that saw him miss nearly three months earlier this season.
"He will not be with us tomorrow, that is clear, after that we will see," Madrid coach Zinedine Zidane said on Friday.
"It is a muscular problem, it is where he had his operation.
"When he started to play again it has bothered him.
"It is true that I am concerned. I don't like to see my players injured and even more so in the final straight of the season."
Bale has played just 25 times in all competitions this season due to various injuries and suspension.
Zidane is expected to make a series of changes from the side that started in Munich with the second leg in mind.
Two-goal hero in midweek Cristiano Ronaldo could be rested, whilst Pepe and Raphael Varane are also absent due to injury.
Real have made a positive start to a huge April with Barcelona also visiting the Santiago Bernabeu next weekend.
Zidane's men have opened up a three-point lead over Barca at the top of the table and have a game still in hand.
Meanwhile, they remain on course to become the first team to retain the Champions League in 27 years.
"I think it is the DNA of this club, the more difficult the matches, the more the players respond," added Zidane.
"We are all happy when the end of the season arrives with important matches."
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