The Belgium international returned from a six-game absence in LaLiga as a second-half substitute in Madrid's 2-1 win over Elche on Sunday (AEDT).

It had been hoped the 30 year-old would be ready for more game time, when Madrid host Atalanta in the Champions League last-16 second leg.

However, Hazard had to miss training on Tuesday (AEDT) due to a damaged hip flexor, and manager Zidane confirmed he would not be in the squad for the visit of the Serie A side.

"He's not going to be fit. We're going to put something out shortly [on the injury]; I can't say any more," Zidane said. "Something is going on. These are things I can't explain. I want to be positive and think it's going to be something small.

"They [the fans] have to wait. We know what sort of player he is. They want to see him, of course, just like everyone else here. But now, they can't."

Hazard has played just 14 times this season as injuries continue to blight his time in the Spanish capital.

The €100million signing from Chelsea has only started 29 matches in all competitions since joining two years ago and has not completed 90 minutes in a single game since November 2019.

"There are four questions on Hazard – I can't say any more," Zidane replied when pressed about the player's problems. "We want to help him.

"I don't know if it will be with me or someone else, because he has a long contract, but I want with all my strength for him to be seen as the player he is. Sooner or later, he'll arrive."

Hazard is one of a number of fitness concerns Madrid has had this season but Zidane refused to pin any blame on the club's medical department.

"I don't think there's a problem [with the department]. We have very competent people here who are on top of the players," he said. "We're going to find out what is happening, but at the moment, it's inexplicable. We've talked about pre-season, the accumulation of matches, also in the head.

"We're going to try to recover [the injured players]. Now, we have fewer injuries. Enough of them have returned."

Striker Karim Benzema, meanwhile, was left saddened by Hazard's latest setback, saying: "He hasn't had much luck since he came here.

"I'm sad because he's a top player. He's sad because he wants to show that he's a world star. We need him."