Arsenal suffered an injury blow when defender Kieran Tierney was forced off with what looked like a shoulder problem during the first half of Monday night's Premier League clash with West Ham.
The Scotland international appeared to suffer the injury after colliding with Michail Antonio while defending a West Ham free-kick.
He was replaced by Sead Kolasinac, who was only promoted to the bench half an hour before kick-off when Hector Bellerin suffered an injury in the warm-up.
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