Hazard had just returned from a three-month layoff when he suffered an ankle injury against Levante at the weekend.
Tests carried on the former Lille attacker by the Real Madrid medical team revealed a fracture to his right distal fibula.
Hazard’s latest injury will see him miss Real Madrid’s UEFA Champions League round of 16 clash against Manchester City on Wednesday and the El Clasico against Barcelona at the weekend.
Although Real Madrid have not confirmed how long Hazard will be out for, reports in Spain suggest he could be out for another two months.
Zidane did not sound too optimistic when queried by reporters about Hazard’s chances of featuring again for Los Blancos this season.
"I can't tell you. It is hard to say," he said at a news conference ahead of Wednesday's last-16 first leg with City.
"We don't know if he will be operated on, but he's obviously not happy. He had been out for almost three months and then played two games and picked up an injury.
"Obviously it is very bad news for him, but I can't tell you if he's going to be back before the season is over."
Hazard joined Real Madrid in a big-money move from Chelsea in the summer but is yet to set the Santiago Bernabeu alight with the exceptional performances he is usually associated with.
The 29-year-old has scored just one goal and provided one assist from 15 appearances across all competitions for Real Madrid this season.
