Sanchez fit to start for Chile against Japan in Copa America
Sanchez is Chile's top scorer with 41 goals and helped the team win the last two editions of the Copa America, but is coming off a disappointing and injury-plagued season with Manchester United when he was often relegated to the bench even when fit.
The 30-year-old Sanchez scored only once in 20 matches with the English club.
"He is coming off a tortuous season, it is hard for him," Rueda said at a news conference, adding that Sanchez may not be fit for the full 90 minutes.
"He has the conditions to start, that is possible. Lasting the 90 minutes is what we will analyze," Rueda said.
The coach also said striker Nicolas Castillo and left back Jean Beausejour could be out of Monday's match at the Morumbi stadium in Sao Paulo. Castillo has a muscular problem in his left leg, while Beausejour injured his left heel.
Rueda said both are expected to return to training within days.