Arsenal boss Mikel Arteta admits Oleks Zinchenko missed today's clash at West Ham due to injury.
Arteta confirmed the 26-year-old picked up a muscular problem during the 2-2 draw at Liverpool last Sunday.
The Spaniard said before kickoff: "A muscle issue.
"At the end of the match at Anfield last week, he was struggling the last few minutes.
"We assessed him and he wasn't fit enough to play, but that's why we have good players like Kieran [Tierney] to replace him."