Portugal’s coach, Paulo Bento, could be in trouble after appearing to question the integrity of the Serbian referee, Milorad Mazic, following Monday’s heavy defeat by Germany.

Bento’s team went from rated to ragged inside 45 minutes of their opening World Cup game, presenting Germany with an easy 4-0 victory and losing three players in the process. Hugo Almeida and Fábio Coentrão were brought off with muscle strains and Pepe will definitely miss the next match, against the USA on Sunday, after picking up the dumbest of red cards eight minutes before the interval. Coentrão is out for at least 10 days and Bento is not confident of having Almeida back in time to face the USA.

“There were two occasions when the referee showed bias, first with the penalty and then with the sending off,” the Portugal coach said. “I am not saying it was only the referee’s fault. We also made mistakes but the circumstances of what happened in the first half made the rest of the game difficult for us.”

In reality Portugal made life difficult for themselves. Most referees at the tournament would have awarded the penalty against Coentrão that allowed Thomas Müller to score the first of his three goals, from the spot. It could be argued that the defender did not literally pull Mario Götze over but he was clearly using his arms to impede the German’s progress.

The sending-off decision was even more clear cut. Pepe took it upon himself to admonish Müller for play-acting by sticking his head into his opponent’s face. The referee saw it as a headbutt, Müller was sitting on the turf, not doing anything to provoke such a response, and a player with Pepe’s experience, albeit one with a reputation for volatility, badly let down his team-mates in a game of such significance. Not that Bento was willing to point the finger at his defender.

“The sending-off was forced on the player,” he said, somewhat opaquely. “I don’t know if it was because of Pepe’s reputation. It depends what sort of a reputation you think Pepe has.” As of now, it is an even greater one for unreliability than he had before.

In addition the player Portugal were pinning hopes on, Cristiano Ronaldo, had one of his quieter games. It would be harsh to say he failed to turn up – he tried his best and was lively in the opening stages – but his recent injury seems to have taken a lot of the fizz out of his performance.

“Even before Portugal went down to 10 men we were dominating the game,” Joachim Löw said. “We knew their main attacking threats would be Ronaldo and Nani and we controlled them quite comfortably. We sealed them off. We said before the start that our only option was to try and win this game – any other result would have been unacceptable – and we made an excellent opening to the World Cup.

“It was very hot on the pitch and the players noticed that the temperature was taking a toll on fitness but fortunately we were able to establish a winning lead quite early in the game. Any coach has to be satisfied with 3-0 at half-time, whatever the conditions.”

Germany did not come through completely unscathed. Mats Hummels had to leave the pitch with a thigh strain, though thanks to Müller’s hat-trick, the first of the tournament, they were never in trouble. “It was an uphill struggle for Portugal in the second half,” the Bayern Munich striker said. “It was a great start for us, we played an excellent game, but this was just the opener. We have two more group games to play and the focus remains on reaching the knockout stages.”

Müller more than justified Löw’s faith in putting him in the starting line-up ahead of Miroslav Klose, Germany’s other prolific scorer. “Thomas has an instinct for creating dangerous situations,” Löw said. “He is unorthodox and unpredictable and that makes it very difficult for opponents to read his intentions. He is just an innate goalscorer.”

Lukas Podolski dedicated the result to Michael Schumacher, though confirmation that the racing driver had left hospital came as news to Löw. “If that is true, it is great news for everyone,” he said. “Michael has the best wishes of all of us.”