Naby Keita has pulled out of the Guinea squad with a lower back injury and the flu.
Keita, who will join Liverpool in the summer, was substituted 68 minutes into RB Leipzig's 2-1 win over Bayern Munich on Sunday.
The midfielder put in a man-of-the-match performance as Leipzig inflicted a first defeat on Bayern after they went unbeaten for 18 consecutive games.
He cancelled out Sandro Wagner's lead and set up Timo Werner for the deciding goal before being withdrawn.
Leipzig, who shared an update on Keita's fitness on their website, said he would miss the friendly against Mauritania on Saturday but did not say how long he will be sidelined.
Austria international Marcel Sabitzer had already been substituted in the 10th minute with an injury.
"Sabitzer sustained a ligament tear in his right ankle in the match against Bayern Munich," the club announced. "It remains unclear how long he will be sidelined."
RB Leipzig are sixth in Bundesliga and trail Eintracht Frankfurt, currently fourth, by only two points.
Meanwhile, Keita's future Liverpool teammate Dejan Lovren will miss Croatia's two upcoming fixtures with a foot injury.
Lovren has been left out of Croatia's preliminary 29-man squad for friendlies with Peru and Mexico in the United States, the Croatian Football Federation announced.
The centre-half sat out Liverpool's 5-0 win over Watford prior to the international break because of a minor ankle injury.