Mikel Arteta confirmed Bukayo Saka and Willian both picked up injuries against Leeds United on Sunday.
Both players had to be withdrawn in the 0-0 draw at Elland Road.
Asked about Saka, Arteta said: "He was in pain.
"We're going to have to assess with the medical staff how bad it is, but it looked like a pretty bad challenge and he was in pain so we decided to take him out straight away."
Willian was replaced by Reiss Nelson at half-time, with Arteta explaining: "He was feeling something muscular and we had to take him off."