Real Madrid forward Eden Hazard is a serious doubt for his side's Champions League last-16 first leg game at home to Manchester City and next week's 'Clasico' with Barcelona after hurting his ankle in Saturday's 1-0 defeat away to Levante.
Hazard had been kept out of action for almost three months by an ankle injury and was making only his second appearance since his return, but he hobbled off midway through the second half and was seen wearing an ice pack on his right foot.
"I think it's a knock to the same area where he suffered his last injury and it does not look good," Zidane told reporters.
Hazard is Real's joint-record signing but has struggled with injuries since his 100-million-euro (83.64 million pounds) move from Chelsea last June, missing the start of the campaign with a muscle problem before hurting his ankle against Paris St Germain on Nov. 26.
Real, who have lifted a record 13 European Cups, play against Premier League champions City on Wednesday at the Santiago Bernabeu and then face another crucial game on Sunday at home to Barcelona.
Madrid's defeat to Levante followed last week's surprise 2-2 draw at home to Celta Vigo and meant they fell off the top of the standings and were replaced by Barca, who trounced Eibar 5-0.
Before facing Celta, they had won their last five league games in a row.
"We have dropped five points in two games but it is what it is," added Zidane.
"We had a very good first half but we couldn't find a goal and then they score with their first chance and that hit us hard.
"It's football and it's really tough but I don't think we deserved this today because our boys gave everything. Now we have to keep our heads up, realise what has happened and look to the next two games where we have so much at stake."