Sanches, a loan signing from Bayern, is hoping that he can be ready to help Swansea during the last few weeks of the season. The club are still in a relegation fight.
"He is progressing," Carvalhal told reporters on Thursday.
"In the beginning they said it could be long-term, but I believe he will come back next month. That's my feeling – I think he will be back sooner than we expect."