Germans want to take early advantage against Northern Ireland

Germany's Leroy Sane, Sami Khedira, Bastian Schweinsteiger, Emre Can, Jerome Boateng, Lukas Podolski, Mesut Ozil and Joshua Kimmich during training.

 Germany must come out firing from the first minute when they meet Northern Ireland on Tuesday or they could risk giving the underdogs the confidence to spring a surprise in their final Euro 2016 group game, centre back Mats Hummels said.

The Germans need a win to guarantee first place in the group, while Northern Ireland could go through to the last 16 even if they lose.

But with top spot ensuring a meeting with a third-placed team in the next round, the world champions will want to send a strong message to the tournament favourites after an average defensive display against Ukraine and a toothless attacking performance against Poland in their opening games.

"We know that there is the possibility to give them the confidence to beat us if we let them, so we will try to be the better team from the first minute so they don't start believing in themselves," Hummels told reporters on Monday.

Northern Ireland, whose team is made up of few star names, are compact and have shown a togetherness that make them hard to defeat. They beat Ukraine 2-0 to notch their first win in a major tournament in 34 years, after narrowly losing against Poland in their opener.

The last time Northern Ireland beat Germany was in 1983 during the golden years of their national side.

They have conceded three goals on average in their last four games against them with their last confrontation in 2005 ending in a 4-1 friendly defeat.

"It's not a big surprise that we don't know that much about Northern Ireland," Hummels said.

"But British teams are often very similar in their style of play. We played Scotland and Ireland in the qualifiers and we saw how strong these teams can be physically, mentally and they play with passion."

He said it was key for the team to learn as much about their opponents in the 24 hours prior to the match because playing an unknown team sometimes can prove complicated.

"If you've played a few times against players you know their tricks, but that's not the case with the Northern Ireland players. We'll need to analyse."

Assistant coach Thomas Schneider said there could be a few changes in the German line-up on Tuesday, but he declined to elaborate.