The Belgium international was signed by Real Madrid from Chelsea in a big-money move in 2019 but has struggled to make an impact in the Spanish capital.
Hazard only managed 22 appearances and one goal in his debut season at Real and injuries have kept him out in 2020-21, playing 14 times and scoring three goals.
After his latest lay-off, he returned with 15 minutes off the bench in Saturday’s 2-1 win over Elche but Real boss Zinedine Zidane revealed he won’t be part of Tuesday’s last 16 second leg.
“He is not fit to be with us. I can’t tell you any more because I can’t explain these things to you,” Zidane said.
“I hope it’s not much because we have to be positive. Something is happening. He’s a player who’s never been injured or not been injured much in his career and this is a new situation for him. I can’t explain any more.
“We’re there for him and we want him to get better. I hope he’ll be back with us soon.
“Our fans have to wait for him. We know the type of player he is and we want to see Eden playing, that’s obvious, but at the moment it can’t be the way he wants it to be and we’ll be patient and wait. He has a long contract.
“I want our fans, all the people who work here, to see the player Hazard is. And this is going to come sooner or later. We have to be patient.”
Real holds a narrow 1-0 advantage from the first leg away to Atalanta, but Zidane acknowledged the Italians will head to Madrid determined to win and have the firepower to turn the tie around.
“I think they’ll come here and look to win the game, I’ve no doubt about that,” he said.
“We have to put in a great performance to be able to progress. We played the first leg, we won, but for us it doesn’t mean anything. We have to play the second leg and it’s going to be very difficult for us.”