Lukaku, who is of Congolese descent, scored two well-taken goals to lead Belgium to a 5-2 romp over Tunisia in an end-to-end game on Saturday which also saw Eden Hazard come into his own with a superb double.
While Tunisia are no worldwide football powerhouse, they nevertheless managed to find their way into the Belgian box often enough in the first half and even briefly cut the deficit to make it 2-1.
Belgium were aiming to firmly establish their World Cup credentials as they toook on Tunisia in Moscow.
Lukaku clipped a right-foot shot over advancing goalkeeper Farouk Ben Mustapha in first-half stoppage time.
"So, when you have to change that many players, you put more pressure on your defenders but I think the Belgium team deserved to win".
The highest average number of goals scored at a World Cup was in Switzerland in 1954, with an incredible 140 goals in 26 games - an average of 5.4 per match.
Belgium's quick goal from the penalty spot against Tunisia ensured there were no 0-0 draws in the first 27 matches of a World Cup for the first time. In that case Tunisia would be eliminated on zero points.More news: Mohamed Salah considering quitting Egypt team over Ramzan Kadyrov row
Belgium opened with a 3-0 win over Panama 3-0 and another win against Tunisia would nearly certainly secure a place in the knockout stages from Group G.
Belgium are ranked third in the world, behind only Germany and Brazil, but Martinez said there was no room for complacency against Tunisian, ranked 21.
Secondly, Maaloul's decision can be seen as a reaction to the injury crisis that affected Tunisia in the run up to the tournament. Belgium then claimed a 1-0 victory in a friendly in June 2014. Belgium's goal difference of plus-six is another big factor in the unlikely event of a three-way tie.
Belgium cruised to a 5-2 win at Spartak Stadium and the result meant that all 27 games so far at Russian Federation 2018 have seen at least one goal - beating the previous record of 26 matches in a row set in Switzerland in 1954.
Romelu Lukaku, Dries Mertens and Eden Hazard again lead the attack in an unchanged Belgium lineup for the World Cup game against Tunisia.
A lot of the drama at this World Cup has had little to do with the football so far.
Vardy was an unused substitute in the 2-1 win over Tunisia and faces one of the toughest battles for game time given he is effectively challenging for the same position as captain Harry Kane.