Wirtz's injury comes after a productive international break for the 22-year-old. Germany booked their place in next summer's World Cup with victories over Slovakia and Luxembourg.
During Die Mannschaft's 6-0 win over Slovakia earlier this week, Wirtz was influential, setting up Leroy Sane for the third goal with a brilliant diagonal ball. The playmaker was mobbed by his teammates in the aftermath, perhaps as a sign of solidarity as Wirtz continues to struggle to adapt to life in the Premier League.
German boss Julian Nagelsmann again defended his player during the international break. He said: "We all know what he's capable of, and it's perfectly normal for a player of his age to go through a bit of a dip in form. We can't expect him to perform at the same level for three years straight. Instead, we all need to support him a little bit so that he can clear his head here, and then maybe Liverpool could also help him out by scoring some of the chances he creates. That would be one idea, because he does not create few chances, it's just that... they somehow don't like to shoot the ball in, that's also part of the truth."