Arsenal defender Gabriel Magalhaes limped off for Brazil with what appeared to be a groin injury in the second half against Senegal on Saturday.
Brazil have already qualified for the World Cup and were participating in a friendly against the Lions of Teranga at Arsenal's Emirates stadium, with Gabriel starting in a back four.
The Gunners man was unable to see out the game as he went down clutching his groin in the 63rd minute, and he was eventually replaced after being treated by medical staff.
Gabriel has arguably been the best centre-back in the Premier League this season, and his potential absence will be a concern for Mikel Arteta, especially as the club have come to rely on his impact from set pieces.
With a game against fierce rivals Tottenham Hotspur on November 23, even a short spell on the sidelines would almost certainly rule him out of the North London derby.
How long could Gabriel Magalhaes be out for?
Mikel Arteta will hope that the centre-back's injury is only minor, and if the defender has been fortunate, then a grade 1 injury would only see him miss out on one to two weeks of action.
The Gunners will play Tottenham on November 23, Bayern Munich on November 26 and Chelsea on November 30, and there is a chance that the Brazilian could miss all three matches.
A grade 2 injury would involve a partial tear of the muscle, and recovery time can vary, but a player would typically be expected to be out for three to six weeks.
Gabriel will hope to have avoided a grade 3 injury as that would involve a complete tear of the muscle or tendon, and there are risks of complications if surgery is required.
The 27-year-old would require at least two to three months of recovery, though surgery could lead to a longer absence.
How will Mikel Arteta line up against Tottenham Hotspur?
Arsenal defender Riccardo Calafiori is capable of playing as a centre-back, but he has been ruled out of Italy's World Cup qualifier against Norway on Sunday due to a hip issue, and may therefore miss out against Tottenham.
William Saliba is certain to be selected in the middle of a back four, and considering Gabriel could miss out against Spurs, the most likely candidate to partner him is either Cristhian Mosquera or Piero Hincapie.
Mosquera has already impressed this campaign, with the defender showcasing his talent against the likes of Liverpool and Newcastle United, whereas Hincapie has played just 28 minutes of Premier League football.
Arteta cannot afford to take risks against Tottenham, so that could mean Mosquera is set for his third start in the top flight as an Arsenal player.