Tunisia, also without a point after two matches, having extended their 40-year World Cup winless run to 13 games, are also still in with a theoretical chance of making it on through three points.
Group G concludes on Thursday, with England playing Belgium in Kaliningrad and Tunisia facing playing Panama at Mordovia Arena in Saransk.
After also scoring twice in the opening 3-0 win against Panama, Manchester United's Lukaku showed clinical finishing with two first-half goals in Moscow, matching Ronaldo's tally in Russian Federation.
The Tunisians cut the lead when defender Dylan Bronn headed in a goal in the 18th minute, but Belgium weren't done.
The full-back's late challenge on Hazard was deemed, with the use of VAR, to have been just inside the area and the Chelsea man stepped up to crack the resulting spot-kick into the bottom-left corner.
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Ali Maaloul's weak pass on the halfway line was collected by Dries Mertens, who sprinted away and put Lukaku clear.
That goal served to halt Belgium's early dominance, but they did grab a third with nearly the last kick of the half.
Belgium can take a big stride towards the last 16 with a win over Tunisia.
Substitute Batshuayi missed a hat-trick of fantastic chances within five minutes before finally finding the target in the 90th with a good finish.
Khazri scored a consolation deep into stoppage time after a neat swivel in the box, but it mattered little as Belgium comfortably took a giant stride towards the last 16.