Germany's Thomas Mueller celebrates scoring his team's third goal, his second goal for the match, against Portugal during their 2014 World Cup Group G soccer match at the Fonte Nova arena in Salvador, June 16, 2014. [Photo/Agencies]

SALVADOR, Brazil - Thomas Mueller's hat-trick inspired Germany to a ruthless 4-0 mauling of 10-man Portugal in their opening World Cup Group G match on Monday and underlined their credentials as serious title contenders.

Billed as a clash of European heavyweights, the Germans ignored the sizzling Salvador heat to deliver a sizzling attacking display that ensured the game was over as a contest by halftime.

Portugal could not cope with their opponents' pace and movement and were 3-0 down by the interval as Mueller, marking his 50th international, scored either side of a thumping Mats Hummels header.

"Three goals in one match, in the opening match against such an opponent is just great," Mueller, whose side are bidding to end a 18-year title drought, told German television.

"We got into the match really well and had some half chances then suddenly we were ahead 2-0. In heat like this a lead like that is a great advantage."

In their 100th World Cup match, the first team to reach the milestone, Germany were in the mood to party and went 1-0 up on 12 minutes through a Mueller penalty after the clever Mario Goetze wriggled away from Joao Pereira and was hauled down.

Hummels powered home the second from a Toni Kroos corner on 32 minutes before Mueller, top scorer at the World Cup four years ago, stole in ahead of a sleepy Bruno Alves to smash in the third in first-half stoppage-time.

The task was made even harder for Portugal by a needless 37th minute red card for Pepe. The defender, furious at what he felt was "simulation" by Mueller following a slight collision between the two, was sent off for pushing his head into the German's face as he sat on the ground.

The interchanging attack of Goetze, Mueller and Mesut Ozil bamboozled Portugal, whose talisman Cristiano Ronaldo was left a frustrated observer for much of the match as the German midfield dominated proceedings.

WILD SCREAMS

Much had been made of Ronaldo's inclusion after injury problems and although he began the day with wild screams meeting the mere mention of his name, jeers soon rang around the Fonte Nova arena as his infrequent touches came to little and all but one of his trademark free kicks disappointed.

With German Chancellor Angela Merkel watching in the crowd, it was Mueller who took the crowd's appreciation, completing the first hat-trick of the tournament after 78 minute when he prodded home a spilled Andre Schuerrle cross.

The victory extended Germany's run of having won every opening World Cup match since 1990 and they have scored at least four goals in five of those seven games.

"We worked hard to create goal chances, the team played well and didn't let them have many chances," Germany coach Joachim Loew told a news conference.

"We played fast in the first half to get our chances. In the second half it was a different match, to play economically in this heat and keep control of the ball."

The demolition will send a strong message to Germany's rival title contenders in Brazil and left Portugal looking nervously at qualification with games against the U.S. and Ghana to come.

"We have to analyse this in all calm," Portugal coach Paulo Bento said. "We tried in the second half but didn't succeed. We lost the match in the first half and couldn't change that in the second half.

"Germany played well, two right away and three in the first half. Then we lost Pepe. Our counter attacks didn't really succeed either."