"He had a scan two days ago and he's out for a while - I don't know is it two weeks or one more week, but he will not be available".
However, the Frenchman insists Sanchez remains "focused" on playing for the Gunners this season amid continued speculation about his future.
PSG, Bayern Munich and Manchester City have all been mentioned as potential suitors of Sanchez, who is in the final year of his deal at the Emirates Stadium.
"No, we have not", Wenger was quoted as saying by football.london at his pre-Leicester press conference when asked if he had been in touch with PSG chairman Nasser Al-Khelaifi "It's a long time I didn't speak to Nasser, because it's certainly very busy to complete the transfer of Neymar and it's a long time that I didn't speak to him".
"When a player goes into the final year of their contract we will try to extend the contract because there is no reason we shouldn't do it, but we are not there yet", he said.
"I have plenty of uncertainties about the players who didn't play against Chelsea", he said blithely enough. I do not think we necessarily need to either, as long as his fellow countryman Per Mertesacker is back in the starting line-up, which he should be.
While Ozil and Ramsey missed the Community Shield, Mertesacker was taken off injured after sustaining a head injury. Alexis [Sanchez] will not be available for example, so I can not go into the game with too many uncertainties.
Wenger said: "I think if you read the French papers they are on Mbappe's case to finish their transfer market".