The striker featured in the whole of Saturday's 1-1 draw at Manchester United despite suffering a hamstring injury while on international duty with Chile.
Sanchez, who scored twice for his country while carrying the injury, was a doubt for the Old Trafford clash right until the morning of the game.
He was strapped up last weekend and played the whole 90 minutes in a match where team-mate Olivier Giroud equalised with just a minute left.
The 27-year-old Sanchez has started more games than any other Arsenal player this season, scoring eight goals, and could be rested for Wednesday's Champions League tie at home to Paris Saint-Germain.
This time last season he was forced to sit out almost two months with a similar injury.
But veteran manager Wenger defended his selection policy after suggesting it was a "suicidal decision" for him to play in Chile's win over Uruguay.
"He had a bit of tightness in his hamstring, but he was checked before the game," Wenger said Tuesday.
"I follow the instructions of the medical staff and the player. If they declare him capable of playing, and the player does as well... I have never forced anyone to play in my life.
"I've never demanded anyone should be injected to play. If a player is 100 percent, I make a decision. But the suggestions I have forced him to play are wrong, completely wrong," the Frenchman explained.
"I had the luxury to give (Mesut) Ozil a break because Germany didn't pick him. Sanchez was not overloaded with games before United, either, as he didn't play in Colombia."
Giroud has started only once all season but has scored four goals in his last four club appearances.
"They are different style of players," Wenger said of Sanchez and Giroud.
"That dictates a different style to us as well. The shape and form of the players of the moment, their hunger... it's a mixture of many ingredients.
Asked if he saw Giroud, who was sent off in the 1-1 draw in Paris earlier in the season, as an "impact player, Wenger replied: "No, not really. I have only good players.
"Every week I leave top players on the bench. I rotate as well, a little bit. Olivier Giroud has been out a long time and is ready now to compete again.
"It will change game to game, and I will make rotations, but he will not be on the bench forever. He will have opportunities. I have not decided yet (if he will start)," he added.