Eden Hazard is set to miss Real Madrid's crucial clashes against Manchester City and Barcelona after suffering a hairline fracture to his right ankle.
The Belgium forward limped off in the second half of Los Blancos' 1-0 defeat to Levante on Saturday and received treatment for the injury on the bench.
Madrid has not said how much time Hazard will miss but reports in Spain suggest another long lay-off meaning the former Chelsea star will not face Manchester City in Wednesday's Champions League last-16 first-leg tie, or Barca in a crucial Clasico in La Liga next weekend.
A club statement read: "Following the tests carried out today [Sunday] on our player, Eden Hazard, by the Real Madrid medical department, he has been diagnosed with a fracture to his right distal fibula.
"His recovery will continue to be assessed."
It marks another blow for Hazard in a debut campaign blighted by injury, the 29-year-old having only returned from another fractured right ankle sustained against Paris Saint-Germain in November last weekend.
The start of Hazard's Madrid career was delayed by a hamstring problem he suffered in August and the timing of his latest setback could hardly have been worse.
Madrid's loss to Levante means it has ceded top spot in La Liga to Barca ahead of the Clasico, while the side's fight for a 14th European crown restarts in a huge clash with Pep Guardiola's City.
Speaking after the game, Madrid coach Zinedine Zidane admitted the initial analysis of Hazard was not promising.
"It doesn't look good," Zidane told reporters at a news conference."It can become weak where you've had an injury. It is a blow, let's see. It's sore now but we'll see tomorrow when we do more tests."
Hazard has made just 15 appearances for Madrid since joining in a big-money move from Chelsea last July.