The 28-year-old suffered a thigh injury during the Gunners 4-1 win over Stoke City at the weekend.
Wenger said it ‘did not look good’ for the Chilean and confirmed he is set to undergo a series of tests later today.
‘Sanchez will have a test today to see [whether he can face Sunderland],’ Wenger said. ‘Yesterday it didn’t look too good but with him you never know as he’s so keen.
‘It was just a kick to his thigh so possibly he can recover for tomorrow.’
Meanwhile, Wenger said experienced defender Laurent Koscielny is struggling with a calf problem, although the rest of the squad is at his disposal.
‘Koscielny has a little problem – it’s a reoccurrence of his calm injury,’ the Frenchman said.
‘Everyone else is available except for Alex Oxlade-Chamberlain.’