Arsenal defender Andre Santos faces a spell on the sidelines after injuring his ankle in Tuesday's 3-1 defeat to Olympiakos in the Champions League.
Santos was one of just two starters from the weekend to make the trip to Greece despite being Arsene Wenger's only fit left-back.
The injury to Santos leaves Wenger with a selection headache as Kieran Gibbs is still recovering from a stomach problem.
"Santos suffered a bad ankle injury. He looks like he will be out for a while. We have Kieran Gibbs coming back in two to three weeks," said Wenger.
"Hopefully Santos will not be too long but, for Saturday against Everton, he looks to be short."
Arsenal could move into fourth with victory over Everton on Saturday afternoon.
