The 21-year-old was named in Senegal's starting XI for their friendly against Brazil in London but was forced off shortly after the interval. Sarr walked from the pitch alongside the national team's medical staff after a clash with Manchester United forward Matheus Cunha.
The severity of the issue remains uncertain, but with the derby against Arsenal only days away, his withdrawal has caused immediate concern at Tottenham.
Thomas Frank, already navigating one of the most extensive injury crises in the Premier League, now faces the possibility of being without more than a dozen first-team players for the derby.
Cristian Romero only recently returned before the break, but fellow summer arrival Randal Kolo Muani suffered a setback in the 2-2 draw with Manchester United. Additionally, Mohammed Kudus was unavailable for that match after sustaining a knock the previous week.
Tottenham's midfield depth has also been tested further with Lucas Bergvall returning early from Sweden duty due to lingering concussion symptoms stemming from the loss to Chelsea. He had already missed Spurs' final two fixtures before the international break.
There is some optimism: Archie Gray, Ben Davies, and Dominic Solanke continue their push toward full fitness, while Dejan Kulusevski and Radu Dragusin are steadily recovering from knee issues. Their potential availability could soften the blow should Sarr be ruled out.
