Arteta said the pattern is unusual, noting it has happened only once or twice in his six years at the club but four times this season. He said the club is looking into the warm‑up routines.
The most recent case involved Riccardo Calafiori, who was withdrawn before the Wigan match. Earlier, William Saliba was ruled out at Anfield and Bukayo Saka missed the Leeds trip after a warm‑up pull‑up.