The Arsenal attacking midfielder has had an underwhelming season so far since making a £65million move to north London from Chelsea, with his lack of form seeing him fall down the pecking order for the national team.
But, rather than drop Havertz completely, Nagelsmann opted to use him in the rather unfamiliar position of left-back against Turkey on Saturday night.
Although he gave away a late penalty in Berlin that secured a 3-2 win for the visitors, he also netted his side’s opening goal and largely gave a solid display with his manager even suggesting he could make the role his own ahead of next summer’s European Championships.
‘Kai said he wanted to do it, wanted to try it,’ explained Nagelsmann afterwards.
‘I don’t see this as a risk for him, but as a very, very big opportunity to play a key role at the Euros. For a first time in an unfamiliar position, he did extremely well and probably was our best player.’
But Matthaus, Germany’s most-capped player, is not convinced by Havertz’s position change despite an encouraging performance against Turkey and says he needs to be picked further forward – and perhaps even lead the line.
Writing in his column for Sky Germany, Matthaus said: ‘Havertz brings a lot of quality, but he was not trained in this position, but in the offensive [areas] and mainly centrally.
‘I accept that the national coach wanted to try something out, but I hope it doesn’t happen again – even though Havertz was one of the better players against Turkey.
‘If we want to have his qualities in the team, we have to find a place where he can show the extra class that he partly embodied during the last World Cup.
‘It can’t be a permanent solution if we suddenly let one of the best German offensive players of recent years play full-back.
‘This is also a slap in the face to those who have played there recently, even if there were problems on the left side of the defence recently.’
He added: ‘After Havertz’s goal, it initially looked as if Nagelsmann’s plan might work, but as a coach you have to think long-term, not just from one game to the next.
‘The world-class quality that Nagelsmann sees in Havertz has so far only shown on the offensive.
‘At Bayern, Nagelsmann didn’t necessarily rely on a nine, so he could use Havertz as a false nine, Leroy Sane on the right, Jamal Musiala in the middle and Florian Wirtz on the half-left or left side. Then you would have gathered all the world-class players that Nagelsmann and I see in one team.’