Lukaku's place in the team had been questioned by some following the 2-0 defeat to Italy in Belgium's tournament opener, yet Chelsea forward Hazard insists his compatriot never let any criticism affect him.
"Lukaku showed how good a player he is," Hazard told UEFA.com. "For a striker it's always great for confidence to score goals. He scored goals in the friendly games we played, but he was criticised a little.
"When a striker doesn't score, he tends to get criticism.
"But he can take it, he's mentally strong and I am sure he will be the difference for us in each game, I hope."
Belgium coach Marc Wilmots will hope the 23-year-old can fire them to victory again in the crucial clash with Group E rivals Sweden in Nice on Wednesday.