Manchester United boss Erik ten Hag says Anthony Martial has suffered an Achilles injury.
For today's trip to Southampton, Martial is absent again, having missed the first two Premier League matches with a hamstring complaint.
Ten Hag said: “Casemiro is fit. He did all the training sessions. He trained first individually and the last days he trained with the team.
“Martial came out with a problem on his Achilles, out of the game, so we have to wait.
“I cannot tell a prognosis, how long it takes. I hope he will be available for the next game."