With Chelsea drawing 1-1 in Madrid, the La Liga giant have to score and Zidane made no attempt to play down how important Hazard could be.
The Belgian is looking to put his old club to the sword and prevent another all-English Champions League showpiece after Manchester City got past Paris Saint-Germain on Tuesday night to reach their first ever final.
“It is a great time for him to flick a switch and I think he is prepared and that is very good for us,” Zidane said.
“But I am not going to tell you now whether Sergio will play or any other player.”
Thomas Tuchel meanwhile sent out a message to his Chelsea players to be brave against Real Madrid in the Champions League semi-final.
The German then promptly sent them home to their wives and girlfriends so they stand the best chance possible of being able to stand up and be counted.
The Chelsea manager believes that defending their narrow 2-1 lead from Madrid a week ago is not about tactics.
He said: “It’s not about the formation, it’s not about what Real Madrid play, it’s about how we play, what intensity we have, what belief we have, are we brave enough, do we play courageously enough and do we play at our top level within the formation.”
To that end, he needs his players on top of his game and the 47-year-old feels his players stand the best chance by being properly relaxed with a night in their own beds.
Moreover, he has told his men not to report to the team hotel until lunchtime.
“When we have evening games I sometimes feel it will increase the tension if you go to a hotel the night before,” he said. “So let them go home, let them be a bit distracted.
“We will meet for lunch because that still gives us another seven or eight hours together in the hotel and that is enough for me to do meetings.
“And to have several hours of rest again, so if somebody had a bad night or did not sleep well it is time to recover.”