Hazard was expected to fill the void left by Cristiano Ronaldo following his £150million move from Chelsea but he has suffered from a horrid run of injuries while he has come in for criticism about his weight.
But Courtois says: "Hazard? I have no doubt, I am sure we will see the best Eden Hazard.
"He is the first with the desire to show it. I see him very well and hopefully soon he can prove it.
"Just before his injury, he played several games very well and there he had such bad luck and getting out of that was not easy.
"But now this month I saw him train very well. I am sure that in no time he will explode and will to give many joys to the team."