Hazard’s Chelsea side will face Messi and Barcelona in the Champions League last-16.
The Belgian playmaker has been likened to Messi and is tipped to one day win the Ballon d’Or.
Ronaldo won the award in 2017 for his fifth gong, which puts him level with Messi.
But Hazard, speaking to Chelsea TV, says Messi is his pick for the best ever.
“Of course, when you are playing football you want to play against the best,” he said.
“The best team, the best players in the world.
“Messi is the best player in the world.”
Hazard, 26, played 73 minutes of Chelsea’s 2-0 win over Brighton today before coming off injured.
He has been linked with a move to Real Madrid next summer, although Chelsea will likely battle hard to keep him at Stamford Bridge.
The Sun claimed before Christmas that Manchester United were even lining up a deal for the player.
But a move to one of Chelsea’s domestic rivals appears unlikely.