Romelu Lukaku scored just before halftime to give Belgium a 3-1 lead over Tunisia and equal Cristiano Ronaldo's tally of four goals so far at the World Cup. Tunisia cut the deficit when Dylan Bronn headed in from a free-kick.
"We respect Tunisia's threat but they're a team that need to come out and win the game, so they'll make it very, very open", he said.
Despite cruising to a routine 3-0 victory over Panama in their Group G opener, there were still one or two niggling doubts regarding Roberto Martinez's style of play despite the obvious talent at his disposal.
Belgium were dominant from the outset, taking a 2-0 lead inside 16 minutes through Hazard's penalty and Lukaku's fine finish.
Hazard won the penalty when he was brought down by Tunisia's Syam Ben Youssef on the edge of the area.
These two countries have previously met at the 2002 World Cup in Korea, where they shared the spoils in a 1-1 draw. England (three points) face Panama (none) on Sunday in the same group.
Tunisia coach Nabil Maaloul swapped his goalkeeper with Farouk Mustapha taking over from Mouez Hassen, who played in the opening 2-1 defeat to England, failing to stop Harry Kane scoring the late victor for the Three Lions.
Things quickly got worse for Tunisia when Ali Maaloul's heavy touch on the halfway line allowed Dries Mertens to nip in and release Lukaku, who found a flawless low finish.
Romelu Lukaku and Eden Hazard scored two goals each in a dominant Belgium display on Saturday, leading their team to a 5-2 win against Tunisia in the highest scoring game of the Soccer World Cup.