Real Madrid confirm thigh muscle injury for Hazard
The Belgium international was substituted after just 28 minutes of Saturday's 2-1 home loss to Alaves, as Real were beaten for the third time in La Liga this season.
Real did not provide a timeline for Hazard's return, but local media reported he could be ruled out for at least two weeks.
Hazard appeared to be caught by an Alaves defender as he dribbled the ball in the area after his shot was saved, and was pictured grimacing moments later with his hands on his knees.
Real coach Zinedine Zidane had initially suggested it was just a "simple knock" based on the feedback at the time from Hazard.
The 29-year-old has featured in just 28 of 65 matches for Real since joining from Chelsea last year for 100 million euros ($119.6 million).
He missed the start of this season due to injury and then tested positive for coronavirus on November 7.
Real face Shakhtar Donetsk in Ukraine in the Champions League on Tuesday knowing victory will clinch a place in the last 16 of the competition.