Arsenal boss Mikel Arteta admits he's unsure of Takehiro Tomiyasu's injury.
Tomiyasu was forced off during victory over Wolves.
Arteta said: "He felt something.
"I don't know if it was fatigue. We decided to change straight away and we didn't want to take any risks. Let's assess him and see how he is."
Tomiyasu was forced off on 78 minutes and replaced by Ben White.