Eden Hazard's injury misery continued on Monday after Real Madrid confirmed the attacker had hurt his right thigh in their weekend loss to Alaves.
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.
The Spanish champions said in a statement that Hazard, 29, had been diagnosed with an injury to his right quadriceps and that his "recovery will continue to be assessed".
Real did not provide a timeline for Hazard's return, but local media reported he could be ruled out for at least two weeks, which would mean missing both of their two remaining Champions League group matches.
He will also likely be unavailable for Real's upcoming league matches against second-placed local rivals Atletico Madrid and Sevilla, who sit in fifth, just one point and place behind the 13-time European champions.
"It's a complicated situation for him, for the club, for everyone, because we all want to see him play with us," coach Zinedine Zidane told reporters on Monday ahead of Real's Champions League clash with Shakhtar Donetsk.
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.
Zidane had initially suggested it was just a "simple knock" based on the feedback at the time from Hazard.
Hazard 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.
"He'd never injured himself before during his entire career. At 28-29 years old he picked up an injury that bothered him for a while and there little niggles that keep resurfacing," Frenchman Zidane added.
"We have to accept it, try to get through it, and I'm sure he'll come back even stronger, and soon."
Real face Shakhtar in Ukraine on Tuesday knowing victory will clinch a place in the last 16 of the competition.
They sit second in Group B, one point behind leaders Borussia Moenchengladbach and three ahead of Shakhtar. Their final group match is against Moenchengladbach in Madrid next week.