Toni Kroos has warned that Germany's 4-0 victory over Portugal will count for nothing if they cannot maintain that form throughout the tournament.
Joachim Low's men are determined to end their long wait for silverware after falling just short in their last four major tournaments, and the demolition of Portugal raised hopes that they can go all the way in Brazil.
However, Kroos told a news conference on Wednesday: "It was a good start, certainly, but nothing more. We are here with the big goal of winning the World Cup, and we will need to bring that form to the pitch in all seven games.
"It was good for our confidence to have a good start, and we've done that. Now we think about our second game."
There had been concerns that Germany's build-up to the tournament had not gone as planned, but the Bayern Munich midfielder insisted he was "not surprised" by the manner in which they had performed in their opener.
"I know what qualities we have," he said. "We can always deliver a performance like that although, of course, we were curious to find out where we are at after the preparations."
Germany will take on Ghana on Saturday looking to firm up their position as Group G leaders and knowing that three points would make qualification all but certain.
However, Kroos has warned that it is important that they remain fully focused amid the wave of euphoria that has already swept over Germany.
"We need to keep both feet planted firmly on the ground," he said. "As of now, we have achieved nothing."
Kroos was one of the star performers during the Portugal match, covering 11.7 km and playing 78 passes, with 88 percent reaching their destination.
When asked about his passing game, the 24-year-old -- who refused to discuss his contract situation at Bayern -- insisted good distribution was a prerequisite for his role.
"That's just something that is important for my game, and it's also important to not give away too many balls in central midfield -- that always hurts you," he said. "And that's why you have to limit the amount of times you lose the ball. Passes have to be precise and well timed for you teammate to pick them up. That's my goal, and I work for that.
"I feel fine playing the more attacking role, taking shots at goal, and playing the final ball, but also I like to set up the play with low passes."