(REUTERS) – Belgium outclassed underdogs Tunisia with an impressive display of speed, power and attacking football but they will quickly need to improve their defence if the country’s golden generation are to live up to expectations and go far in this World Cup.

The Belgians completely overran their opponents from the start, feeding Romelu Lukaku up front. The towering all-time leading goalscorer for his country (40) could not be stopped, scoring twice to take his tournament tally to four in two games.

Belgium’s first two goals, including an Eden Hazard penalty, in a span of 10 minutes were reward for exactly that early pressure, along with many more scoring chances.
Roberto Martinez’s side, who emerged as 3-0 winners in their opening Group G game against Panama, were always two steps faster than the North Africans.

With Hazard and Kevin De Bruyne wreaking havoc in midfield and the firepower of Lukaku and Michy Batshuayi up front, Belgian fans have every right to expect big things from the Red Devils in this tournament, especially after their 5-2 victory turned out to be their highest scoring World Cup win ever.

Their attacking prowess was always going to be their strength at the tournament and their impressive display in Moscow’s Spartak Stadium yesterday, which took their goal tally to eight – as many as Russia – from two matches, merely confirmed their status as a genuine outside bet for the title.

But Martinez must urgently take a closer look at his team’s defensive operation which more than once allowed the Tunisians to take a stab at Thibaut Courtois’ goal.
While Tunisia are no international 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.

It was only after Tunisia ran out of steam in the second half and Martinez introduced Marouane Fellaini that order was restored.
The Belgians would be wise to remind themselves of Euro 2016 when they reached the quarter-finals but surprisingly crashed out to underdogs Wales, with their backline falling apart.

Belgium’s at-times sloppy passing and repeated loss of possession by their holding midfielders against Tunisia may be lost amid the enthusiasm of their big victory which all but assures them a spot in the knockout stage.

But their weakness will not have gone unnoticed by their next Group G opponents, England, and all their potential rivals in the next round.