Having Dries Mertens and Romelu Lukaku capable of scoring the way they did against Panama helps.

"People know I am supposed to score goals," Lukaku said. "The most important thing to me is to win matches."

Lukaku scored twice in a six-minute span in the second half after Mertens' perfectly struck volley gave Belgium the lead, as the Red Devils beat overmatched Panama 3-0 to top Group G.

Saddled with massive expectations and a line-up of talent the envy of other teams in the tournament, Belgium showed flashes of being a team worthy of being world champions.

A shaky first-half performance by Belgium was replaced by a confident, attacking group in the second that was finally able to find gaps in Panama's defenve and convert those chances into goals.

"In the World Cup you have to play 90 minutes," Belgium coach Roberto Martinez said.

"You have to be aware that in any game you go into, if you don't score early on, you have to be prepared to work hard and go through periods in which you are tested."

The two goals from Lukaku came shortly after Mertens scored from about 18 yards in the opening moments of the second half, finally relieving some pressure after Belgium was unable to break down Panama for the first 45 minutes.

Lukaku's first goal came 20 minutes later, but the pass from Kevin De Bruyne made it possible. Rather than shooting through a crowd of Panama defenders, De Bruyne cut a pass with the outside of his right foot onto Lukaku's head and into the net.

Lukaku added a second on a breakaway minutes later, chipping Panama goalkeeper Jaime Penedo as he left his net.

"For me it's important to have the right line in the box," Lukaku said. "Usually I'm in the right position at the right time."

Panama played their style - physical, aggressive, sometimes looking more like wrestling than soccer - and managed to hang with the Red Devils for longer than expected.

They were called for 18 of the game's 35 fouls and shown five yellow cards of the eight dished out.

But they never created threatening scoring chances and eventually Belgium took complete control.

"We are a team that is very organised, we play tactically," coach Hernan Dario Gomez said.

"Sometimes we may look tough but the other teams are tough and physically strong as well."

Panama need a result against England, who edged Tunisia 2-1, in their next game to keep their tournament hopes alive.

Belgium will be favoured to account for Tunisia as the group's big guns eye off a battle for top spot in the final group game.

Australian Associated Press