Sanchez could need ankle surgery, says Chile coach
Sanchez went off with an ankle problem in the 88th minute of the goalless draw in Alicante on Saturday.
Chile play Guinea on Tuesday in another friendly, also in the Spanish resort, but Rueda said he was worried that the former Arsenal and Manchester United player might miss the start of South American World Cup qualifying in March.
"We have to see what diagnosis they make in the club, because it is decisive for us," the Chilean coach said. "If there is surgery we could lose him two to three months, if not, it could be a matter of weeks. That depends on the club. They own the player."
Sanchez has left the Chilean training camp and returned to Milan.
Inter have yet to provide official information about the severity of his injury.
"For us, Alexis is very important," Rueda said. "For Inter, he's just another player. If he gets injured, buy another one."