The Chile international has been ruled out for the start of the new Premier League season and will miss the first game of the campaign against Leicester City on Friday.
It also looks likely he will be absent for the trip to Stoke on August 19 after Wenger confirmed the setback on Wednesday.
The Gunners boss is unsure how long the 28-year-old will be injured for but admits it will be at least a fortnight so he may also be doubtful for the clash at Liverpool on August 27.
"Sanchez will not be available," Wenger said. "He had a little abdominal strain that he caught in training on Sunday morning before he came to Wembley.
"He had a scan two days ago and he's out for a while. I don't know [how long he will be out] - two weeks, one more week. He will not be available.
"He will not play at Stoke."
Sanchez has been the subject of plenty of speculation this summer as he has under a year left on his current contract and does not appear close to signing new terms with Manchester City very interested in the former Barcelona man.