However, following Arsenal's 5-2 victory over Benfica in the Emirates Cup on Saturday, Wenger confirmed that the club are aware of his illness and have given the Chilean some extra time off in order to fully recover from a bout of flu and reduce the chances of it spreading among the rest of the squad.
Sanchez, who is entering the final year of his contract, is set for showdown talks with Wenger.
Sanchez is in the final year of his Arsenal contract and is reportedly keen to move on after Arsenal finished fifth in the Premier League last season, depriving the attacker of Champions League football this term.
Responding to the question of Sanchez has told him he wants to stay at the club despite interest in him, Wenger said: "I can not reveal a secret conversation".
"Do you really think they sit in the dressing room and think: "Oh I have one year to go I will not play well today".
But Gibbs, who was ill, Francis Coquelin, who needs a scan on an ankle ligament injury, and Shkodran Mustafi, who is only just back in training after the Confederations Cup, are all unlikely to face Chelsea in the Community Shield at Wembley on Sunday.
"The performance on the day doesn't depend on the length of contract". Every situation is different. It's normal. Nobody knows if Sanchez will not extend his contract with us as well here.
The Chile worldwide has yet to begin pre-season training with his team-mates following his exertions at the Confederations Cup in Russian Federation, helping the Copa America champions to reach the final.
Asked whether it was an issue that he would have six players out of contract, Wenger said.
"I went to Russian Federation nearly with the idea of not taking part because I wasn't in good condition", he said.