The Argentine, alongside current Juventus man Cristiano Ronaldo, has dominated the game over the last decade, breaking countless records with his club while also becoming the first man to win five Ballons d'Or.
Messi or Ronaldo has been a constant source of contention amongst some football fans, with endless debates generated over the question of who is the best in the world.
But for Hazard, only one man has a legitimate claim to that title.
"Two G.O.A.T.s (Greatest of All Time) you say? No way. There is only one G.O.A.T: Him, Lionel Messi!" the Chelsea man explained to HLN.
"Those two games against Barcelona were not my best memories of 2018. I was happy to play against Barcelona and Messi, but I didn’t deliver what I expected. I was disillusioned.
"My three sons were there for the home match at Stamford Bridge. The eldest is a big Messi fan - all of us are Messi fans, actually. He wanted to see Messi that day, because Messi is a special player."
One of the teams the Red Devils upset along the way was Brazil, who went down 2-1 in the quarters thanks largely to an inspired performance in goal from Thibaut Courtois.
The much-questioned Neymar was comforted by Hazard at the final whistle, and he admits that he felt for Brazil's icon after the match.
“That was something that came naturally. I didn’t think about it when we crossed each other. I just put myself in his place," he added.
"Everyone expected him to become the best player of the World Cup. It had to be Neymar. Lionel Messi was out of the tournament. Cristiano Ronaldo as well. The pressure on his shoulders must have been immense.
"I know the feeling. But tens of thousands of times bigger than in Belgium, when they expected a lot from me in 2014. The nation, the fans, the journalists. It was Neymar, Neymar, Neymar. It was all about Neymar, Neymar, Neymar.
"It was exaggerated hysteria. Have we won? Then it’s thanks to Neymar. Have we lost? Then it’s Neymar’s fault. As if those 22 others in the Brazil squad didn’t even participate.
"We did not speak - his English isn’t that good. It was all about the gesture, not about the words. In a difficult moment I wanted to make him feel respected. To comfort him. He is a top player. His moment will come. Maybe at the next World Cup.“