The Germans beat Ukraine 2-0 in their first match in Group C, but were then held to a 0-0 draw by Poland.
"Last week it was all about the defense, now it's offense," Germany coach Joachim Loew said Saturday at the team's tournament base, appearing relaxed before his side's final group game against Northern Ireland in Paris on Tuesday.
"We will win against Northern Ireland. We will win the group and then, I believe, we'll be playing in Lille again for the round of 16," the 56-year-old coach said. "I don't know about any other ways."
Germany's first game in Lille against Ukraine exposed defensive weaknesses, with Manuel Neuer forced to make a number of saves and Jerome Boateng to make a goal-line clearance in the 2-0 win. There was improvement with Mats Hummels returning to shore up the German defense against Poland at Stade de France on Thursday, but Loew acknowledged that his side would have to do more in attack.
"We created hardly any chances in the final third. There was something lacking in the runs forward, the path to goal, the speed going forward. We spoke about this after the game and it showed in the analysis yesterday," Loew said, adding that Germany's lack of creativity was not fitness-related.
"The team is in good physical shape, absolutely. I can't find a specific reason because our team normally creates chances in every game."
A draw against Northern Ireland would be enough for Germany to qualify for the round of 16 from Group C. Germany, with four points, leads Poland on goal difference. The Poles play already-eliminated Ukraine in Marseille on Tuesday. Northern Ireland would go through with a win and will finish third in the group with a draw or loss.
Germany's lack of cutting edge against both Ukraine and Poland has done little to suggest the side can emulate France and Spain's feat of following a World Cup win with the European title. Against Ukraine, the side needed Shkodran Mustafi, a defender, to break the deadlock before Bastian Schweinsteiger sealed the win on a break in injury time.
Loew said the issue wasn't a question of who was playing up front, with much of the discussion centering on whether Mario Gomez, an out-and-out striker, would be a better option than "false nine" Mario Goetze, who has started both games so far.
"With the two central defenders they had, the Poles couldn't be troubled by crosses. It was the same against Ukraine and it will be the same against Northern Ireland. If we're playing high balls from the middle of the pitch then we're playing into their hands," Loew said. "We need to play the ball forward at pace from different positions, from midfield, from the wings, and to have many people going forward to score goals. It has nothing to do with having a central striker in the middle."
Boateng bruised his hip in the draw with Poland but Loew said the Bayern Munich defender will be fit for Tuesday's game. He also said there would be "one or two changes" for the game and he paid tribute to Northern Ireland for being "a positive surprise in the tournament."
"In qualification they were a strong fighting side, extremely strong in challenges, like you expect the British and the Irish to be," Loew said. "In their first game they held back a bit against Poland, they didn't play as they can, but in the second game they displayed unbelievable fight, lots of power and a huge amount of energy."
Germany's players had the day off Saturday and Loew said it was vital for their conditioning over a long tournament.