The Chile forward is out of action with a hamstring problem but is due to return to training on Monday - one week before City visit the Emirates Stadium in a match which could swing the balance of an ever-changing title race.
Sanchez, 26, picked up his injury in the 1-1 draw at Norwich a fortnight ago with Wenger having to defend his decision to play the former Barcelona man after revealing his hamstring had been affecting him leading up to the game at Carrow Road.
The Gunners have seven first-team regulars out of the picture due to injuries but Sanchez is unquestionably the most valuable asset Wenger has on the shelf.
There is no way he will return in time for Sunday's trip to bottom side Aston Villa but the Arsenal boss said, with the type of player Sanchez is, he could be involved against Manuel Pellegrini's side on December 21.
"He is back on Sunday, he trains on Monday morning at 9.30am," Wenger explained.
"He is running already..
I sent him back to Chile, where he has been running with the physio of the national team, and we will see what kind of state he is in next week.
"He may be a bit short for City, certainly, but with Alexis you never know."
With Sanchez sidelined this weekend, Wenger is likely to start with Theo Walcott out wide and the in-form Olivier Giroud as the main striker.
The France international scored a hat-trick in Wednesday's 3-0 win in Olympiacos which sealed Arsenal's place in the Champions League knock-out stages.
Sometimes labelled as a player not good enough to fire Arsenal to trophies, Giroud now has 26 goals for the calender year, with 10 in his past 12 appearances, and Wenger was full of praise for the 29-year-old.
He believes his trio of attacking players can rival the world's best strikers and feels there is no-one better than Giroud at doing the less attractive tasks of a centre-forward.
When asked if he would rank Giroud alongside the likes of Sergio Aguero, Robert Lewandowski and Karim Benzema, Wenger replied: "Of course, and Walcott as well.
"We have Walcott, Sanchez, Giroud who can all scores goals
They have different styles and that is very important as well.
"I never questioned the fact he (Giroud) will be a very needed striker here
If you go on counter-attack of course he is not the kind of player that you want or select first.
"That is why when we played against Bayern I chose Walcott because you know you play more in your own half and you have to go out quickly.
"When you dominate the game and need presence in the box there is no better player than Olivier."
Wenger was widely criticised for not signing a new striker over the summer but he reckons that, in not splashing the cash on a player who would be seen as a replacement for Giroud, he has injected some belief into a player who fired unfancied Montpellier to the French title four seasons ago.
"He is in a big club and you have to accept to be questioned," Wenger added.
"And I believe he can live with that and is used to it now and overall I think as well I heard someone saying if he is on the market tomorrow he would find anywhere, so that show you as well the kind of striker he is
You do not find a lot (of them)."
Source : PA