Lukaku grabbed two goals for Belgium in a 2-1 win over Switzerland, with the United striker impressing leading the line for his country.
Hazard is the Premier Leagues top scorer and in-form player, and Chelsea welcome Lukaku to Stamford Bridge when club action resumes on 20 October.
And the Chelsea forward joked he would prefer if Lukakus form dipped when he returns to Manchester.
Its not a good sign that Romelu scored tonight, because Im playing against him with Chelsea very soon, Hazard told RTL after the game.
If he scores with Belgium its fine, but it would be a good thing if he does not with Manchester United.
Lukaku and United have endured a difficult start to the season, but the 25-year-old has still managed four goals in eight appearances.
Belgium boss Roberto Martinez was full of praise for his No.1 striker after his 45th goal for his country.
Romelu is a sensational goalscorer, his stats speak for themselves, Martinez said.
What he has been doing on the international level in the last two years says enough. He is one of the best-performing goalscorers today.
This win is very satisfying because it was a difficult match against Switzerland, who wanted to play.
Of course we can play better football but must also be able to find solutions in this kind of game.