Then forward picked up a thigh injury in Sunday's 4-0 victory over Hungary, a performance he described as his best ever in a Belgium shirt. He was substituted in that game and also missed training on Tuesday.
"I hope so, I really hope that he will be able to train tomorrow (Thursday) but he still has some pain in his thigh today so he'll receive care for that this evening," Wilmots told a news conference at the team base in Le Hallain, near Bordeaux.
"We are working on getting him 100 percent fit but I cannot give you a specific time when that will happen nor can I tell you that he will be okay. I would like to but I can't. The medical staff are working on it."
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It would be a big blow if Hazard fails to recover in time for Friday's showdown with Wales in Lille. The Chelsea player was in dazzling form against Hungary, scoring a superb individual goal and contributing an assist for another.
Belgium will head north to Lille, which is just across the border from home, on Thursday.
Although favourites to beat Wales, Belgium's players said it would a tough game for the world's second-ranked side. Wales have had the edge on them in recent encounters, beating them 1-0 in Cardiff and drawing in Brussels in the Euro 2016 qualifiers.
"It's a difficult team. They are very good defensively, they play with three defenders behind," Belgium winger Dries Mertens said.
"They give you the feeling you can score a goal but in the end they score a goal and have stopped you. If you don't play really well against them, you have a lot of problems. They also have a lot of quality up front."
Asked if they had a special plan to counter Wales talisman Gareth Bale, Mertens said breaking down their defence was the main task.
Belgium defender Jordan Lukaku noted that Bale was not the only dangerous Welshman.
"We will try to neutralise Aaron Ramsey and Bale because they are the strongest players Wales have. So we will find a way to counter them but it will not be one player, it will be the whole team," Lukaku said.
(Reporting by Angus MacSwan; Editing by Ken Ferris)
