The manager fears the winger will burn out over the Christmas period but says the club's injury crisis means he has to pick him
The winger has played 69 matches for Arsenal since joining 15 months ago alongside a busy international schedule for Chile.
Sanchez was given a short leave of absence to sit out Arsenal's pre-season tour of Singapore after winning the Copa America with his country in the summer.
However, Wenger feels he is now unable to give him the rest his body craves due to the injuries to fellow attackers.
"I am worried because before he went away with Chile he was a bit jaded. But if I ask him 'are you tired?' you can guess the answer," he said.
