After racking up two wins and a goal difference of plus-six Belgium are virtually assured of advancing but it is not yet guaranteed - and they will be aware that they will need to tighten up at the back to handle the threat of the big guns deeper into the tournament.
And Belgium, who wrap up Group G against England on Thursday, may confront fitness concerns with Lukaku, who had his right ankle worked on in the first half before coming off in the 59th minute with the result no longer in question.
After the comprehensive 3-0 victory over Panama in their first game, Belgium were always expected to be unchanged for the Tunisia match.
Lukaku is joint tournament top scorer with Portugal's Cristiano Ronaldo on four goals, and with seven goals Belgium's most successful scorer at World Cups and Euros overall, one more than Jan Ceulemans.
Belgium vs. Tunisia - Football Match Report
It was the second-earliest goal scored by a Belgium player at a World Cup after Leopold Anoul scored in the fifth minute in 1954. If Belgium beats Tunisia it will be nearly certainly assured of a place in the knockout stages of the World Cup.
"Today was a different game to Panama, they were very deep and structured, we had to find solutions".
The pressure couldn't be sustained by Tunisia and on the stroke of halftime it was Lukaku who would blow the game wide open.
Belgium were much the better team, looking unsafe on nearly every attack, but they were seriously aided and abetted by some ragged defending and non-existing marking from their opponents.
Hazard won the penalty when he was brought down by Tunisia's Syam Ben Youssef on the edge of the area. Tunisia cut the deficit when Dylan Bronn headed in from a free-kick.
Thomas Meunier played the ball through the defense for Lukaku to beat the offside trap and flick the ball over goalkeeper Farouk Ben Mustapha.
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Juan Quintero's clever free-kick drew the South American side level, however, when he fired low under the jumping wall before half-time.
Substitute Michy Batshuayi made it a rout in stoppage time, and failed with three other good scoring chances.
The ball continued rolling for the Red Devils as Eden Hazard earned Belgium a penalty after five minutes.
"I think 80 percent of the match is based on morale so at the beginning of this match we conceded a goal and then we conceded the second but we were able to score a goal so our morale improved", Maaloul said. "We would like to apologise to the Tunisian fans".
"In that respect, if we look after our performance we'll get settled into that sort of game".
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