Germany began its Group A campaign on Friday (AEST), but was stunned by its host as goals from David Hancko and David Strelec settled the match 2-0 in favour of Slovakia.

After defeats in the UEFA Nations League semi-finals and third-place play-off in June, Germany has now lost three successive competitive games for the first time as a unified nation.

It was also just its second FIFA World Cup qualifying defeat by more than one goal – the other was a 5-1 victory for England in September 2001.

Nagelsmann's side sits bottom of Group A after the first match as a result, with leader Northern Ireland its next opponent in Cologne.

But the 38-year-old, who conceded his side was far from its best against Slovakia, insisted he was not concerned about his job.

"We did not have a perfect day [against Slovakia]. No one had," Nagelsmann said.

"To be frightened is not a good thing. I will try my best to win. I am not afraid. I think we will do a better job than on Thursday [Friday AEST].

"We will try to be the best competitors possible and win our home game, which is very important for us and the fans in the stands. It is such an important game for us."

Nagelsmann named a strong line-up for that match, but has promised to make changes on Monday (AEST) in a bid to get a first win in qualifying.

"We have had some discussions with some players and with the team," Nagelsmann said.

"The team cleared up some things internally as well. We looked at what to expect and developed an idea for tomorrow."

"Content-wise, it will not be a completely changed team tomorrow. But on a personal level, there will be some things that will be happening. We have to deliver a better game."