Sanches is back in South Wales after extended stints in his homeland and at parent club Bayern Munich recovering from a hamstring injury.
“I think he does not have any chance for the World Cup, I told him to put the speculation down," said Carvalhal of his fellow countryman.
“Portugal have a lot of good players but even if he plays well over these games it will be difficult for him. I think he will be out of the World Cup.
“He is disappointed but it is football, he was injured, he is frustrated but the reality is he has to try and help the team this season and make himself better for the future.
“He must be fit and 100 per cent. If he is trying to work his way to the World Cup and training flat out he will get injured again.
“He needs to lower expectations to be fit and get back playing. After three months out it will be difficult for him, it is a big distance between the expectation and the reality."