Arsenal will be without Francis Coquelin for up to four weeks due to a hamstring injury.
Coquelin limped out of Arsenal's 3-3 draw with Bournemouth on Tuesday night with the problem.
The defensive midfielder lasted just 28 minutes at the Vitality Stadium before he was replaced by Alex Oxlade-Chamberlain.
Arsener Wenger voiced concern about Coquelin's injury following the match, but the Gunners boss sounded more optimistic about the 25-year-old's injury when he spoke to the press on Thursday ahead of the FA Cup clash with Preston on Saturday.
"Coquelin is three to four weeks now," Wenger said. "He has a hamstring problem. I say three, four weeks because he came off.
"Maybe we have good news. He has a scan today."
Wenger revealed Lucas Perez sustained an ankle problem against Bournemouth and could miss Saturday's trip to Deepdale along with Mesut Ozil, who has been sidelined with a mystery illness.
"Ozil is coming in today and will be assessed by the doctor," Wenger added. "He has been in bed for two weeks so I cannot imagine he will be involved on Saturday. It's a flu yes, a throat infection, I don't know exactly."