United States international John Anthony Brooks suffered a thigh injury on international duty and could miss Hertha Berlin's Bundesliga meeting with Stuttgart.
Brooks, 22, was among the last players to resume training at Hertha this summer following his appearances for United States at the Gold Cup.
The defender was only used as last-minute substitute in the first two games of the Bundesliga season, and only returned to Hertha's starting XI in the final match before the international break.
Following the 3-1 defeat at Borussia Dortmund, Brooks returned for international duty as Jurgen Klinsmann's men faced Peru and Brazil.
While the Berlin-born defender played the full 90 minutes in the 2-1 win over Peru, he did not feature in the 4-1 loss to Brazil after sustaining a thigh injury in training on Sunday.
Brooks returned to Berlin on Wednesday, and told Bild that he faces a race against time to return to full fitness for his club's meeting with Stuttgart at the Olympiastadion on Saturday.
"I've got problems with the back of my thigh, and so I came straight back [from the national team]," Brooks said. "We'll see on Thursday whether I can make the Stuttgart match."