The Belgian will return to Stamford Bridge for the first time since leaving the club where he made his name.
Hazard will hoping to lift Real past his former club, with the tie currently sitting at 1-1 on aggregate.
"I think everyone at this club only has good things to say about Eden, a lot of praise," Christensen said at a press conference on Tuesday.
"It hasn't changed and we know what he has done for this club. Yes, he is probably going to be a big factor again [on Wednesday].
"I think he has always been a player that brings a lot of happiness and good mood on the pitch. If he has that you will see his quality as well.
"I've seen him grow with the team and the place around him, he was trying to bring that on to the next generation as well.
"We know his qualities and he will probably be a big factor in the game. He's always been someone who brings a lot of quality and happiness to the team. So no matter where he would go he would bring something to the team."