Belgium boss Roberto Martinez thought his team produced a “mature” display as the Red Devils defeated Panama 3-0 in their opening World Cup match.

Belgium, fancied by many to reach the latter stages of the competition, toiled against the Group G minnows during a frustrating first half in Sochi.

Martinez’s men improved after half-time though, with Dries Mertens making the breakthrough at the start of the second half before Romelu Lukaku’s double gave the Belgian’s breathing space.

“I’m delighted. It was exactly what we expected – there are no easy games at the World Cup. We started very well but then became frustrated as the first half wore on,” said Martinez in his post-match press conference.

“But I was delighted in the way the team reacted and the commitment everyone showed to keep a clean sheet.

“In the second half we found our composure and the goal from Dries Mertens, a great goal, was so important for us.

“In a World Cup, you have to play for 90 minutes and we had to be prepared to work hard, show maturity and real togetherness.”

Panama head coach Hernan Dario Gomez felt his side could be proud of their efforts in what was the country’s first ever game at a World Cup.

He said: “I think we have learned a lot from today’s game. It was a very emotional day. The team was still very emotional at the start of the match but as time went by, they were able to focus better.

“It was an incredible experience for our country and I think that our performance was not bad. You’re never happy when you lose but I told my players that they lost with dignity. We will keep growing and learning.”