Belgium international Hazard has been out of action since November after fracturing his ankle in a 2-2 Champions League draw against Paris Saint-Germain.
He has scored one goal and made 13 appearances since arriving from Chelsea for a reported initial fee of €100million, his debut having been delayed until September due to a hamstring problem.
However, Hazard has been in full training with Madrid this week and Madrid coach Zidane confirmed he could feature at the Santiago Bernabeu.
"We all know how important Hazard is and that's why we signed him. He's a great player. We're very happy he's back with the group," Zidane said at a pre-match news conference on Saturday.
"He hasn't played for three months and it's not easy. It will also depend on the game and the rhythm but physically he's absolutely fit and available to be with us.
"We know how much he can help us. It was tough not having him for almost three months due to injury. He's also very happy to be back.
"It's true we have to take it easy, we should give him time, and that's what we did to make sure he's 100 per cent fit when he is back. He is ready to play tomorrow."
Madrid went into the weekend three points clear at the top of LaLiga and face a huge Clasico against Barcelona in between Champions League last-16 matches against Manchester City.
In previous campaigns Zidane has rotated his side heavily for domestic and European matches, but he was guarded when asked about how he will approach the next month.
"The most important game is the one the one that we're playing tomorrow and after that we'll just plan the following week," said Zidane.
"In the next month we'll have very important games and in each game we'll have to give it our all because they are all crucial.
"We've done well up to now but we have to continue like that if we want to win something important at the end of the season. We know the situation and every game will be a tough one, but we're ready for that challenge."