A mystery injury to William Saliba was one of the few sour notes from Arsenal's 1-0 win over Crystal Palace last Sunday.
Eberechi Eze's first-half goal saw the Gunners move four points clear at the top of the Premier League as their excellent start to the season continued.
Is Arsenal's William Saliba available this weekend?
France international Saliba has developed into a key player under Arsenal manager Mikel Arteta and is ranked at no.2 in FourFourTwo's list of the best centre-backs in the world right now.
But this latest issue is not the first time he has been sidelined in 2025-26, having sustained an ankle injury against Liverpool in August which saw him miss the Gunners' next two matches.
Saliba was replaced by Cristhian Mosquera against Palace but Arteta was coy about the nature of the injury post-match.
He said: "Willy obviously had to be out after the first half ... there are two things related to his substitution.
And the Gunners boss also declined to elaborate further when asked ahead of the visit of Brighton, saying only: "We are assessing him.
Mosquera started the Carabao Cup fourth round clash, partnering fellow summer signing Piero Hincapie, with Gabriel - Saliba's usual centre-back partner - coming on as a second-half substitute.
But it was more of the same from Arsenal despite the change in personnel, as the Gunners kept their sixth successive clean sheet in all competitions.
Whether that means Saliba will not be rushed back from his injury remains to be seen and it is unknown if he will return for the trip to Burnley.
Scott Parker's side are on a high after their last-gasp win at rock-bottom Wolves last Sunday and will aim to be the first team to breach the Arsenal defence since Newcastle on September 28.
